Polylactic Acid-polyglycolic Acid Research Articles

Radiographic and complication evaluation of 2 different bioresorbable pins in hallux valgus corrective surgery.

Osteotomies to correct hallux valgus are usually secured using metal implants. Their main disadvantage is the need for a repeat surgery for removal of implanted material. Bioresorbable implants would make it possible to overcome this complication. Few studies analyse the results of using bioresorbable pins. The primary objective of this study is to compare hallux valgus correction radiographic results with the use of two types of bioresorbable pins. The secondary objectives are to screen for possible complications related to the use of these bioresorbable pins. This is a descriptive, retrospective, single-centre study carried out between May 2018 and May 2022 in the orthopaedic surgery department of the Centre Chirurgical Emile Gallé at the CHRU in Nancy (France). The study involved 105 hallux valgus (98 patients) operated on by open double metatarsal and phalangeal osteotomy. Osteotomies were stabilised with resorbable polylactic acid (PLLA) pins (Arthrex® TRIM-IT® drill pin) in 57 cases (53 patients), and with resorbable polylactic acid-polyglycolic acid copolymer (PGLA) pins (Bioretec® ActivaPins®) in 48 cases (45 patients). The efficacy of hallux valgus correction was analysed in terms of changes in preoperative and postoperative radiographic parameters at 1 and 6 months on a weight-bearing foot. Descriptive statistics were used to describe the demographic and radiological parameters of each group. The mean age was 59.7 years (range 25-81 years) in the PLLA group and 56 years (range 23-78 years) in the PGLA group. The mean preoperative HVA was 30° (range 15-63°) in the PLLA group and 30.8° (range 15-57°) in the PGLA group. The mean preoperative IMA was 14.4° (range 7-30°) in the PLLA group and 13.8° (range 7-20°) in the PGLA group. There was a statistically significant correction of hallux valgus in the PLLA (p=5.24 X 10-15 ) and PGLA (p=3.56 X 10-13 ) groups. The mean correction for the hallux valgus angle was 13° in the PLLA group and 12° in the PGLA group. There was no statistically significant difference in hallux valgus correction between the PLLA and PGLA groups, particularly in terms of hallux valgus severity. There was no radiological or clinical complication in the groups related to bioresorbable pins. The use of bioresorbable pins allows effective stabilisation of osteotomies to correct hallux valgus. There was no significant difference in correction between PLLA and PGLA implants, regardless of the severity of the hallux valgus. We did not observe any obvious clinical or radiological complications related to their use. The use of bioresorbable osteosynthesis material in forefoot surgery seems to offer interesting advantages, providing patients with safer and less invasive treatment solutions.

Evaluation of PRF and PLA-PGA Membrane Along with Hydroxyapatite Crystal Collagen Fibers Bone Graft in the Treatment of Infrabony Defects.

The present study was carried out to compare the effectiveness of leukocyte platelet-rich fibrin (L-PRF) membrane and polylactic acid-polyglycolic acid (PLA-PGA) membrane along with hydroxyapatite crystal collagen fibers bone graft in the treatment of human infrabony defects using cone beam computed tomography. A total of 28 systemically healthy patients was chosen which were found appropriate after initial therapy. Each group comprises of 14 defects, according to randomized parallel design. The group A was managed by hydroxyapatite crystal collagen fibers bone graft in conjunction with L-PRF membrane, while group B was treated by hydroxyapatite crystal collagen fibers bone graft in conjunction with PLA-PGA membrane. Clinical and radiographic measurements were recorded at baseline and 6 months postoperatively. Statically significant difference was seen in mean probing pocket depth (PPD), mean R-CAL, and DD from baseline to 6 months in group A and group B but there was no statically significant difference in mean PPD reduction (0.35 ± 1.90 mm), mean R-CAL gain (0.28 ± 1.85 mm) and DD reduction (0.12 ± 1.42 mm) seen at 6 months when compared between both the groups. At 6 months post-surgery both treatment modalities demonstrated statistically significant improvements with regards to CAL gains, PPD reduction, and reduction in radiographic defect depth. Platelet-rich fibrin (PRF) membrane and PLA-PGA membrane along with hydroxyapatite crystal collagen fibers bone graft are useful in the treatment of infrabony defect. Platelet-rich fibrin membrane with hydroxyapatite crystal collagen fibers bone graft have shown to be better in regeneration of bony defect as PRF membrane has growth factors which help in bone regeneration.

Effects of catgut embedding and PGLA embedding at "Zusanli" (ST 36) on skin mast cells, substance P and histamine in healthy rats

To observe the effects of catgut embedding and polyglycolic acid/poly-lactic acid (PGLA) embedding at "Zusanli" (ST 36) on the activation of local skin mast cells (MC), and expression of substance P (SP) and histamine (HA), and to explore the mechanism of the temporal stimulation effect of acupoint catgut embedding and provide a foundation for further research on the initiation mechanism of acupoint catgut embedding. One hundred and sixty male SPF-grade SD rats were randomly divided into a blank group (10 rats), a sham-embedding group (50 rats), a catgut group (50 rats), and a PGLA group (50 rats). Each intervention group was further randomly divided into five subgroups according to the time points after intervention: 8 hours, 3 days, 7 days, 14 days, and 21 days, with 10 rats in each subgroup. One-time sham-embedding, catgut embedding and PGLA embedding was given at left "Zusanli" (ST 36) in each intervention group, respectively. The skin and subcutaneous connective tissue of the left "Zusanli" (ST 36) were collected at the corresponding time points after intervention, except for the blank group (only one day before intervention). Toluidine blue staining was used to detect MC count and degranulation, and immunohistochemical staining was used to detect the expression of SP and HA positive cells. There was no significant difference in MC count between the subgroups of each intervention group and the blank group (P>0.05). There was no significant difference in MC count between the subgroups of the catgut group and the PGLA group (P>0.05). The MC count in the 8-hour subgroup of PGLA group was higher than that in the 8-hour subgroup of catgut group (P<0.05), while the MC count in the 21-day subgroup of PGLA group was lower than that in the 21-day subgroup of catgut group (P<0.05). Compared with the blank group, the degranulation rates of MC were increased in the 8-hour and 3-day subgroups of sham-embedding group, 8-hour, 3-day, and 7-day subgroups of catgut group, and 8-hour, 3-day, 7-day, and 14-day subgroups of PGLA group (P<0.01, P<0.05, P<0.001). There was no significant difference in the degranulation rate of MC between the subgroups of the catgut group and the PGLA group (P>0.05), and no significant difference in the degranulation rate of MC between the two embedding groups at the same time point (P>0.05). Compared with the blank group, the expression of SP positive cells was increased in the 8-hour subgroup of sham-embedding group, 8-hour, 3-day, 7-day, and 14-day subgroups of catgut group, and 3-day, 7-day, and 14-day subgroups of PGLA group (P<0.001, P<0.05). The expression of SP positive cells in the 7-day subgroup of catgut group was higher than that in the 8-hour subgroup of catgut group (P<0.05), while the expression of SP positive cells in the 14-day subgroup of catgut group was lower than that in the 7-day subgroup of catgut group (P<0.001). The expression of SP positive cells in the 7-day subgroup of PGLA group was higher than that in the 3-day subgroup of PGLA group (P<0.05), while the expression of SP positive cells in the 14-day subgroup of PGLA group was lower than that in the 7-day subgroup of PGLA group (P<0.01). There was no significant difference in the expression of SP positive cells between the subgroups of the two embedding groups at the same time point (P>0.05). Compared with the blank group, the expression of HA positive cells was increased in the 8-hour, 3-day subgroups of sham-embedding group, 8-hour, 3-day, 7-day, and 14-day subgroups of catgut group, and 8-hour, 3-day, 7-day, 14-day, and 21-day subgroups of PGLA group (P<0.001, P<0.01, P<0.05). The expression of HA positive cells in the 14-day subgroup of catgut group was lower than that in the 7-day subgroup of catgut group (P<0.05), while the expression of HA positive cells in the 3-day subgroup of PGLA group was higher than that in the 8-hour subgroup of PGLA group (P<0.05), and the expression of HA positive cells in the 14-day subgroup of PGLA group was lower than that in the 7-day subgroup of PGLA group (P<0.05). The expression of HA positive cells in the 3-day subgroup of PGLA group was higher than that in the 3-day subgroup of catgut group (P<0.05). Catgut and PGLA embedding at "Zusanli" (ST 36) in healthy rats could induce changes in local skin MC, SP, and HA, which may be one of the mechanisms of the temporal stimulation effect after acupoint embedding. There are certain differences between different suture materials. A moderate inflammatory response in the acupoint area, mediated by MC and involving SP and HA, may be one of the initiating factors for the effect of acupoint catgut embedding.

Viability and Adhesion of Periodontal Ligament Fibroblasts on a Hydroxyapatite Scaffold Combined with Collagen, Polylactic Acid-Polyglycolic Acid Copolymer and Platelet-Rich Fibrin: A Preclinical Pilot Study.

Background: Conventional periodontal therapy relies on bone regeneration strategies utilizing scaffolds made of diverse materials, among which collagen, to promote cell adhesion and growth. Objective: To evaluate periodontal ligament fibroblast (HPdLF) cell adhesion and viability for periodontal regeneration purposes on hydroxyapatite scaffolds containing collagen (HAp-egg shell) combined with polylactic acid–polyglycolic acid copolymer (PLGA) and Platelet-Rich Fibrin (PRF). Methods: Four variations of the HAp-egg shell were used to seed HPdLF for 24 h and evaluate cell viability through a live/dead assay: (1) (HAp-egg shell/PLGA), (2) (HAp-egg shell/PLGA + collagen), (3) (HAp-egg shell/PLGA + PRF) and (4) (HAp-egg shell/PLGA + PRF + collagen). Cell adhesion and viability were determined using confocal microscopy and quantified using central tendency and dispersion measurements; significant differences were determined using ANOVA (p < 0.05). Results: Group 1 presented low cell viability and adhesion (3.70–10.17%); groups 2 and 3 presented high cell viability and low cell adhesion (group 2, 59.2–11.1%, group 3, 58–4.6%); group 4 presented the highest cell viability (82.8%) and moderate cell adhesion (45%) (p = 0.474). Conclusions: The effect of collagen on the HAp-egg shell/PLGA scaffold combined with PRF favored HPdLF cell adhesion and viability and could clinically have a positive effect on bone defect resolution and the regeneration of periodontal ligament tissue.

In Vivo Degradation Studies of PGA-PLA Block Copolymer and Their Histochemical Analysis for Spinal-Fixing Application.

Polylactic acid (PLA) and polyglycolic acid (PGA) are well-known medical-implant materials. Under the consideration of the limitations of degradable polymeric materials, such as weak mechanical strength and by-product release through the biodegradation process under in vivo environments, PLA–PGA block copolymer is one of the effective alternative implant materials in the clinical field. In our previous study, two types of extremely effective PGA–PLA copolymers (multi/tri-block PGA–PLA copolymers) were synthesized. These synthesized block copolymers could overcome aforementioned issues and also showed good biocompatibility. In this study, the PGA–PLA block copolymers with large molecular weight were synthesized under the same chemical scheme, and their bio durability was confirmed through the in vivo degradation behavior and histochemical analyses (by hematoxylin and eosin and immune staining) in comparison with commercial PLGA random copolymer (medical grade). Specimens for the degradation test were investigated by SEM and X-ray diffractometer (XRD). As a result, the synthesized PGA–PLA block copolymer showed good biocompatibility and had a controlled biodegrading rate, making it suitable for use in resorbable spinal-fixation materials.

Immune-Inflammatory Responses of an Acellular Cartilage Matrix Biomimetic Scaffold in a Xenotransplantation Goat Model for Cartilage Tissue Engineering.

The rapid development of tissue engineering and regenerative medicine has introduced a new strategy for ear reconstruction, successfully regenerating human-ear-shaped cartilage and achieving the first clinical breakthrough using a polyglycolic acid/polylactic acid (PGA/PLA) scaffold. However, its clinical repair varies greatly among individuals, and the quality of regenerated cartilage is unstable, which seriously limits further clinical application. Acellular cartilage matrix (ACM), with a cartilage-specific microenvironment, good biocompatibility, and potential to promote cell proliferation, has been used to regenerate homogeneous ear-shaped cartilage in immunocompromised nude mice. However, there is no evidence on whether ACM will regenerate homogeneous cartilage tissue in large animals or has the potential for clinical transformation. In this study, xenogeneic ACM assisted with gelatin (GT) with or without autologous chondrocytes was implanted subcutaneously into goats to establish a xenotransplantation model and compared with a PGA/PLA scaffold to evaluate the immune-inflammatory response and quality of regenerated cartilage. The results confirmed the superiority of the ACM/GT, which has the potential capacity to promote cell proliferation and cartilage formation. Although there is a slight immune-inflammatory response in large animals, it does not affect the quality of the regenerated cartilage and forms homogeneous and mature cartilage. The current study provides detailed insights into the immune-inflammatory response of the xenogeneic ACM/GT and also provides scientific evidence for future clinical application of ACM/GT in cartilage tissue engineering.

Regeneration of elastic cartilage with accurate human-ear shape based on PCL strengthened biodegradable scaffold and expanded microtia chondrocytes

Tissue engineering provides a promising approach for auricle reconstruction of microtia. Although the first clinical trial of tissue-engineered ear reconstruction has been performed using in vitro engineered human-ear-shaped cartilage, this approach is not regarded as the clinically available treatment yet, due to individual differences in clinical efficacy. In the present study, the feasibility and in vivo long-term fate of elastic cartilage regenerated with an accurate human-ear shape were explored using polycaprolactone (PCL) inner support strengthened biodegradable scaffold and expanded microtia chondrocytes (MCs) to identify factors that may result in discrepant clinical outcomes. Polyglycolic acid/polylactic acid (PGA/PLA) scaffolds with or without PCL inner support were prepared into different shapes by three-dimensional (3D) printing, hot-compressing, and pre-molding technologies. The expanded MCs were seeded into the scaffolds to evaluate biocompatibility of PCL inner support and its influence on cartilage regeneration, tissue integration, mechanical strength, and shape maintenance. The results testified that all the cartilages generated by different patients’ cells were highly consistent in both qualitative and quantitative data, indicating high repeatability and stability of cartilage construction technology. PCL inner support manifested a satisfactory biocompatibility and it had no inhibitory effect on cartilage formation, maturation, and tissue integration. After in vivo implantation, the regenerated cartilage without PCL inner support showed the same level of mechanical strength and shape maintenance ability as the PCL strengthened cartilage. Mature and continuous elastic cartilage with an accurate ear shape could be successfully regenerated in vivo with a long-term shape maintenance. All the cells of regenerated cartilage were derived from the implanted MCs, which could survive and maintain their phenotype for a long time. The current study provides reliable evidence, key techniques, and optimized strategies for further clinical applications of in vitro regenerated cartilage with special shapes such as ear, nose, and trachea.

In Vivo Validation Model of a Novel Anti-Inflammatory Scaffold in Interleukin-10 Knockout Mouse.

We fabricated anti-inflammatory scaffold using Mg(OH)2-incorporated polylactic acid-polyglycolic acid copolymer (MH-PLGA). To demonstrate the anti-inflammatory effects of the MH-PLGA scaffold, an animal model should be sensitive to inflammatory responses. The interleukin-10 knockout (IL-10 KO) mouse is a widely used bowel disease model for evaluating inflammatory responses, however, few studies have evaluated this mouse for the anti-inflammatory scaffold. To compare the sensitivity of the inflammatory reaction, the PLGA scaffold was implanted into IL-10 KO and C57BL/6 mouse kidneys. Morphology, histology, immunohistochemistry, and gene expression analyses were carried out at weeks 1, 4, 8, and 12. The anti-inflammatory effect and renal regeneration potency of the MH-PLGA scaffold was also compared to those of PLGA in IL-10 KO mice. The PLGA scaffold-implanted IL-10 KO mice showed kidneys relatively shrunken by fibrosis, significantly increased inflammatory cell infiltration, high levels of acidic debris residue, more frequent CD8-, C-reactive protein-, and ectodysplasin A-positive cells, and higher expression of pro-inflammatory and fibrotic factors compared to the control group. The MH-PLGA scaffold group showed lower expression of pro-inflammatory and fibrotic factors, low immune cell infiltration, and significantly higher expression of anti-inflammatory factors and renal differentiation related genes compared to the PLGA scaffold group. These results indicate that the MH-PLGA scaffold had anti-inflammatory effects and high renal regeneration potency. Therefore, IL-10 KO mice are a suitable animal model for in vivo validation of novel anti-inflammatory scaffolds.

Comparison of effectiveness of hyaluronic acid in combination with polylactic acid/polyglycolic acid membrane and subepithelial connective tissue graft for the treatment of multiple gingival recession defects in human: A clinical study

Background: The patients today are increasingly conscious of personal appearance, and much attention has been focused on denuded roots that are exposed during smiling which look unesthetic. These concerns have given rise to numerous approaches for covering denuded root surfaces; however, difference of opinions is prevailing among the clinicians. Objectives: Therefore, the present study was undertaken to compare the effectiveness between hyaluronic acid (HA) in combination with polylactic acid/polyglycolic acid (PLA/PGA) membrane with that of subepithelial connective tissue graft (SCTG) for the treatment of multiple gingival recession defects. Material and Methods: Twenty-four systemically healthy patients were randomly assigned to the test guided tissue regeneration (GTR-HA) and control SCTG groups. Clinical measurements, including probing pocket depth, relative attachment level, and relative gingival margin level, were measured at baseline and at the 6-month follow-up. Result and Conclusions: After 6 months, the mean reduction in gingival recession in the test group was 2.55 ± 0.45 mm whereas in the control group, it was 2.11 ± 0.58 mm. The test group showed mean root coverage of 92.93%, and the control group showed 84% at 6 months postsurgery. When HA in combination with bioresorbable PLA/PGA membrane was compared with SCTG group; there was signifi cantly greater root coverage, clinical attachment level gain, and increased width of keratinized gingiva in the test group.

Construction and assessment of bio-engineered intervertebral discs.

The present study assessed the value of bone marrow-mesenchymal stem cells (BM-MSCs) transformed by nucleus pulposus cells (NPs) for engineering of intervertebral discs. BM-MSCs and fetal NPs were cultured, planted onto polylactic acid-polyglycolic acid co-polymer (PLGA) and observed under inverted and scanning electron microscopes. PLGA scaffolds with adherent or suspended BM-MSCs and NPs were implanted into intervertebral discs of New Zealand white rabbits. Intervertebral signal intensity was evaluated by Thompson grading after 12 weeks. Proteoglycan and type II collagen were measured spectrophotometrically and immunohistochemically, respectively. Spindle or multi-angular BM-MSCs developed fibro-like phenotypesin co-culture with NPs and grew with a normal morphology when attached to PLGA scaffolds. A significant difference was observed in intervertebral proteoglycan expression and collagen II expression in the PLGA scaffold group vs. that in the control group implanted with BM-MSCs and NPs without a scaffold (3.93±0.31 vs. 3.52±0.26 mg/100 mg, 12.70±2.83 vs. 9.50±2.06, respectively). Thus, BM-MSCs can be co-cultured with NPs to enhance their differentiation into NPs for disc regeneration. In conclusion, PLGA scaffolds offer viable growing conditions and allow for the maintenance of mechanical properties and spatial structures of the engineered tissue, which meets the requirements of tissue-engineered discs that do not degenerate.

Evaluation of effectiveness of hyaluronic acid in combination with bioresorbable membrane (poly lactic acid-poly glycolic acid) for the treatment of infrabony defects in humans: A clinical and radiographic study.

Background:The combination of biomaterials, bone graft substitutes along with guided tissue regeneration (GTR) has been shown to be an effective modality of periodontal regenerative therapy for infrabony defects. Therefore, the present randomized controlled clinical study was undertaken to evaluate the effectiveness of hyaluronic acid (HA) in combination with bioresorbable membrane for the treatment of human infrabony defects.Materials and Methods:Twenty four infrabony defects in 20 systemically healthy patients were randomly assigned to test (HA in combination with bioresorbable membrane) and control (bioresorbable membrane alone) treatment groups. Probing pocket depth (PPD), relative attachment level, and relative gingival margin level were measured with a computerized Florida disc probe at baseline and at 6 months follow-up. Radiographic measurements were also evaluated at baseline and at 6 months of postsurgery.Results:At 6 months, the mean reduction in PPD in test group and control group was 4.52 mm and 2.97 mm, respectively. Significantly higher clinical attachment level with a gain of 2.20 mm was found in the test group as compared to control group. In addition, statistically significant greater reduction of radiographic defect depth was observed in the test group.Conclusion:Regenerative approach using hyaloss in combination with GTR for the treatment of human infrabony defects resulted in a significant added benefit in terms of CAL gains, PPD reductions and radiographic defect fill, as well as LBG, compared to the GTR alone.

Endothelial Differentiation of Human Adipose-Derived Stem Cells on Polyglycolic Acid/Polylactic Acid Mesh.

Adipose-derived stem cell (ADSC) is considered as a cell source potentially useful for angiogenesis in tissue engineering and regenerative medicine. This study investigated the growth and endothelial differentiation of human ADSCs on polyglycolic acid/polylactic acid (PGA/PLA) mesh compared to 2D plastic. Cell adhesion, viability, and distribution of hADSCs on PGA/PLA mesh were observed by CM-Dil labeling, live/dead staining, and SEM examination while endothelial differentiation was evaluated by flow cytometry, Ac-LDL/UEA-1 uptake assay, immunofluorescence stainings, and gene expression analysis of endothelial related markers. Results showed hADSCs gained a mature endothelial phenotype with a positive ratio of 21.4 ± 3.7% for CD31+/CD34− when induced in 3D mesh after 21 days, which was further verified by the expressions of a comprehensive range of endothelial related markers, whereas hADSCs in 2D induced and 2D/3D noninduced groups all failed to differentiate into endothelial cells. Moreover, compared to 2D groups, the expression for α-SMA was markedly suppressed in 3D cultured hADSCs. This study first demonstrated the endothelial differentiation of hADSCs on the PGA/PLA mesh and pointed out the synergistic effect of PGA/PLA 3D culture and growth factors on the acquisition of mature characteristic endothelial phenotype. We believed this study would be the initial step towards the generation of prevascularized tissue engineered constructs.

Stem Cell-Biomaterial Interactions for Tissue Engineering.

The design of biomaterials and the sourcing for appropriate cells are two integrated aspects of tissue engineering to construct a tissue implant for clinical applications. During the past decades, many innovative biomaterials with desirable biological and mechanical properties have emerged, while stem cells have been shown to be a promising cell source to differentiate into many cell types. However, the testing of these bioartificial tissue constructs in the clinical trials is far from satisfactory. How microenvironments in the biomaterials regulate cellular signaling pathways and functions, how stem cell-derived target cells respond to extracellular cues presented by the biomaterials, and how implanted tissue constructs interact with host tissues remain to be investigated. The information of the interplay between cell and biomaterials would be helpful to guide us in improving our current strategy to refine the tissue constructs for effective tissue repair in regenerative medicine. In this special issue, we first present a thorough review by M. Ramamoorthi et al. on the efficacy of dental stem cell therapy in bone regeneration in preclinical in vivo and in vitro studies. They suggest that well-designed randomized animal trials are needed before moving into clinical trials. Then we introduce three types of innovative biomaterials: (1) bionanocomposites based on bacterial cellulose and magnetic nanoparticles (magnetite) for efficient chronic wounds healing reported by B. Galateanu et al.; (2) the elastomeric poly(e-caprolatone urethane) (PCLU) scaffolds using a high internal phase emulsion for bone tissue regeneration developed by S. Changotade et al.; and (3) a novel gelatin-alginate-polyacrylamide 3D interpenetrating network with superior performance in promoting chondrogenesis using human adipose-derived stem cells designed by S. Dinescu et al. Most importantly, our special focus will be given to the insight studies on the cell-biomaterial interactions. C.-H. Wang et al. demonstrate that the migration ability of bone marrow stem cells can be regulated by varying the porous structure of the artificial ligaments and this regulation is related to the RhoA/ROCK signaling pathway. M. Deng et al. demonstrate the endothelial differentiation of human adipose-derived stem cells on the polyglycolic acid/polylactic acid (PGA/PLA) mesh and propose the synergistic effect of 3D environments and biochemical signals such as growth factors on the acquisition of mature characteristic endothelial phenotype. S. Fu et al. have investigated the protective effect of neuropeptide Substance P on bone marrow stromal cells against apoptosis induced by serum deprivation through Wnt signaling. J. Michel et al. have reviewed a wide range of hydroxyapatite containing scaffolds and their interactions with mesenchymal stem cells in in vitro and in vivo contexts.

Effects of canine myoblasts expressing human cartilage-derived morphogenetic protein-2 on the repair of meniscal fibrocartilage injury

The aim of the present study was to explore the effects of human cartilage-derived morphogenetic protein-2 (hCDMP-2)-expressing canine myoblasts on the repair of meniscal fibrocartilage injury. Purified canine myoblasts were infected with lentiviruses carrying an empty vector or the hCDMP-2 gene. The following four experimental groups were established to study the in vivo meniscal repair in a canine model of meniscal injury: Group A, suture only; group B, suture with the addition of the recombinant hCDMP-2 on a polylactic acid/polyglycolic acid (PLA/PGA) scaffold; group C, a PLA/PGA scaffold with canine myoblasts carrying the empty vector; and group D, a PLA/PGA scaffold with canine myoblasts expressing hCDMP-2. Samples of the regenerated tissue were extracted at weeks 3, 8 and 12 post-repair and analyzed by morphological observation, immunohistochemistry (IHC) and quantitative analysis. At week 12 post-repair, the scaffold material had completely dissolved in the control groups and no changes were observed at the injured area, while regenerated tissue was observed in group D only. Hematoxylin and eosin and Safranin-O staining techniques further revealed cartilage lacunae and fibers present at the red-red zone of the repaired tissue, while cartilage lacunae without fibers were observed at the white-white zone in group D. In addition, IHC studies demonstrated that collagen I and II, and the S-100 protein were expressed at the red‑red and the white-white zones of the repaired tissue in group D. It was concluded that purified canine myoblasts expressing the hCDMP-2 gene were able to promote meniscal fibrocartilage healing by regenerating fibrocartilage-like tissue. The tissue in the red-red zone was regenerated more rapidly than that in the white-white zone. Further studies are required to identify the best way to combine hCDMP-2 growth factor with myoblasts for use in the clinic due to the limitations regarding the clinical use of lentiviral infections.

Carriers in mesenchymal stem cell osteoblast mineralization—State-of-the-art

PurposeTissue engineering is a new way to regenerate bone tissue, where osteogenic capable cells combine with an appropriate scaffolding material. Our aim was in a Medline Search to evaluate osteoblast mineralization in vitro and in vivo including gene expressing combining mesenchymal stem cells (MSCs) and five different carriers, titanium, collagen, calcium carbonate, calcium phosphate and polylactic acid-polyglycolic acid copolymer for purpose of a meta—or a descriptive analysis. Materials and methodsThe search included the following MeSH words in different combinations—mesenchymal stem cells, alkaline phosphatase, bone regeneration, tissue engineering, drug carriers, tissue scaffolds, titanium, collagen, calcium carbonate, calcium phosphates and polylactic acid-polyglycolic acid copolymer. ResultsTwo out of 80 articles included numerical values and as control, carriers and cells, on mineralization and gene expression. β-tricalcium phosphate (β-TCP) revealed elevated alkaline phosphatase activity, and calcium-deficient hydroxyapatite a greater gene expression of osteocalcin when seeded with induced MSCs. ConclusionNo data are published on titanium used as a carrier in MSC osteoblast mineralization. A meta- as well as a descriptive analysis includes numerical values of test materials and of control reactions from carrier and cells, respectively. Only two articles fulfilled these requirements.

Chondrogenic differentiation of bone marrow-derived mesenchymal stem cells induced by acellular cartilage sheets

Acellular cartilage sheets (ACSs) have been used as scaffolds for engineering cartilage with mature chondrocytes. In this study we investigated whether ACSs possess a chondrogenic induction activity that may benefit cartilage engineering with multipotent stem cells. Bone marrow-derived mesenchymal stem cells (BMSCs) isolated from newborn pigs were expanded in vitro and seeded on ACSs that were then stacked layer-by-layer to form BMSC-ACS constructs. Cells seeded on polyglycolic acid/polylactic acid (PGA/PLA) scaffolds served as a control. After 4 weeks of culture with or without additional chondrogenic factors, constructs were subcutaneously implanted into nude mice for another 4 weeks. Cartilage-like tissues were formed after 4 weeks of culture. However, formation of cartilage with a typical lacunar structure was only observed in induced groups. RT-PCR showed that aggrecan, COMP, type II collagen and Sox9 were expressed in all groups except the non-induced BMSC-PGA/PLA group. At 4 weeks post-implantation, cartilage formation was achieved in the induced BMSC-ACS group and partial cartilage formation was achieved in the non-induced BMSC-ACS group, confirmed by safranin O staining, toluidine blue staining and type II collagen immunostaining. In addition, enzyme-linked immunosorbent assay demonstrated the presence of transforming growth factor-β1, insulin-like growth factor-1 and bone morphogenic protein-2 in ACSs. These results indicate that ACSs possess a chondrogenic induction activity that promotes BMSC differentiation.

Improvement of intertrochanteric bone quality in osteoporotic female rats after injection of polylactic acid-polyglycolic acid copolymer/collagen type I microspheres combined with bone mesenchymal stem cells

Osteoporosis mainly involves cancellous bone, and the spine and hip, with their relatively high cancellous bone to cortical bone ratio, are severely affected. Studies of bone mesenchymal stem cells (BMSCs) from osteoporotic patients and animal models have revealed that osteoporosis is often associated with reduction of BMSCs' proliferation and osteogenic differentiation. Our aim was to test whether polylactic acid-polyglycolic acid copolymer(PLGA)/collagen type I(CoI) microspheres combined with BMSCs could be used as injectable scaffolds to improve bone quality in osteoporotic female rats. PLGA microspheres were coated with CoI. BMSCs of the third passage and were cultured with PLGA/CoI microspheres for seven days. Forty three-month-old female non-pregnant SD rats were ovariectomized to establish osteoporotic animal models. Three months after being ovariectomized, the osteoporotic rats were randomly divided into five groups: SHAM group, PBS group, cell group, microsphere (MS) group, and cell+MS group. Varying materials were injected into the intertrochanters of each group's rats. Twenty rats were sacrificed at one month and three months post-op, respectively. The femora were harvested in order to measure the intertrochanteric bone mineral density (BMD) with DEXA and trabecular thickness (Tb.Th), percentage of trabecular area (%Tb.Ar), bone volume fraction (BV/TV) and trabecular spacing (Tb.Sp) with Micro CT. One-way ANOVA and Kruskal-Wallis tests were used. BMSCs seeded on PLGA/CoI microspheres had a nice adhesion and proliferation. At one month post-op, the BMD (0.33 ± 0.01 g/cm(2)), Tb.Th (459.65 ± 28.31 μm), %Tb.Ar (9.61 ± 0.29 %) and Tb.Sp (2645.81 ± 94.91 μm) of the cell+ MS group were better than those of the SHAM group and the cell group. At three months post-op, the BMD (0.32 ± 0.01 g/cm(2)), Tb.Th (372.81 ± 38.45 μm), %Tb.Ar (6.65 ± 0.25 %), BV/TV (6.62 ± 0.25 %) and Tb.Sp (1559.03 ± 57.06 μm) of the cell + MS group were also better than those of the SHAM group and the cell group. The PLGA/CoI microspheres combined with BMSCs can repair bone defects more quickly. This means that PLGA/CoI microspheres combined with BMSCs can promote trabecular reconstruction and improve bone quality in osteoporotic rats. This scaffold can provide a promising minimally invasive surgical tool for enhancement of bone fracture healing or prevention of fracture occurrence which will in turn minimize complications endemic to patients with osteoporosis.

Preliminary study of in vitro chondrogenesis by co-culture of chondrocytes and adipose-derived stromal cells

To explore the feasibility of in vitro chondrogenesis by co-culture of chondrocytes and adipose-derived stromal cells (ADSCs) so as to confirm the hypothesis that chondrocytes can provide chondrogenic microenvironment to induce chondrogenic differentiation of ADSCs. Human ADSCs and porcine auricular chondrocytes were in vitro expanded respectively and then were mixed at the ratio of 7:3 (ADSCs: chondrocytes). 200 microl mixed cells (5.0 x 10(7)/ml) were seeded onto a polyglycolic acid/polylactic acid (PGA/PLA) scaffold, 8 mm in diameter and 2 mm in thickness, as co-culture group. Chondrocytes and ADSCs with the same cell number were seeded respectively onto the scaffold as positive control group and negative control group. 200 microl chondrocytes (1.5 x 10(7)/ml) were seeded as low concentration chondrocyte group. There were 6 specimens in each group. All specimens were harvested after in vitro culture for 8 weeks in DMEM plus 10% FBS. Gross observation, histology, immunohistochemistry, wet weight measurement and glycosaminoglycan (GAG) quantification were used to evaluate the results. Multiple-sample t-test statistics analysis was done to compare the difference of wet weight and glycosaminoglycan(GAG) content between the groups. Cells in all groups had fine adhesion to the scaffold and could secrete extracellular matrix. In co-culture group and positive control group, cell-scaffold constructs could maintain the original size and shape during in vitro culture. At 8 weeks, cartilage-like tissue formed in gross appearance and histological features, and abundant type II collagen could be detected by immunohistochemistry. Wet weight and glycosaminoglycan(GAG) content of co-culture group were respectively (174 +/- 12) mg and (7.6 +/- 0.4) mg. There were respectively 75% (P < 0.01) and 79% (P<0.01) of those of positive control group. In negative control group, however, constructs shrunk gradually without mature cartilage lacuna in histology. In low concentration chondrocyte group, constructs also shrunk obviously with small amount of cartilage formation at the edge area of the construct, and wet weight was (85 +/- 5) mg, which was 37% (P<0.01) of that of positive control group. Chondrocytes can provide chondrogenic microenvironment to induce chondrogenic differentiation of ADSCs and thus promote the in vitro chondrogenesis of ADSCs.

Construction and biological assessment of tissue engineering intervertebral disc

To investigate the value of bone marrow-mesenchymal stem cells (BM-MSCs) transformed by nucleus pulposus (NPs) for construction of tissue engineering disc. BM-MSCs and fetal NPs were cultured in vitro, planted on polylactic acid-polyglycolic acid copolymer (PLGA), and observed with inverted microscope and scanning electronic microscope. PLGA scaffolds with adherent BM-MSCs and NPs, as well as BM-MSCs and NPs suspension were implanted into intervertebral discs of New Zealand white rabbits, respectively. Intervertebral signal intensity was evaluated by Thompson grading 12 weeks later. Proteoglycan and type IIcollagen were determined by spectrophotometric method and immunohistochemistry, respectively. Spindle or multi-angular BM-MSCs turned into fibro-like phenotype coculture of BM-MSCs and NPs, which grew well with normal morphology when they attached on PLGA scaffolds. There was statistical difference in intervertebral signal intensity, and the expression of proteoglycan and type IIcollagen between PLGA scaffolds group and control group (P < 0.05), the content of proteoglycan was (3.93 ± 0.31) mg/100 mg in the PLGA scaffolds group whereas (3.52 ± 0.26) mg/100 mg in the control group. BM-MSCs can be induced into NPs by cocultivation, and PLGA scaffolds can provide good growing conditions, and maintain high mechanical properties and spacial structure which meet the requirement of tissue engineering disc to prevent degeneration.

Experimental study of chondrogenesis in vitro by co-culture of bone marrow stromal cells and chondrocytes

To investigate the feasibility of chondrogenesis in vitro with bone marrow stromal cells (BMSCs) induced by the co-cultured chondrocytes. The BMSCs and chondrocytes were separated from pig and cultured. The supernatant of chondrocytes was used as the inducing solution for BMSCs from the 2nd generation. 7 days later, samples were taken and underwent immunohistochemistry and RT-PCR for detection of the expression of specific type II cartilage collagen, type II collagen and aggrecan mRNA. The cultured BMSCs and chondrocytes were mixed at a ratio of 8:2 (BMSC: cartilage cell) and were inoculated into a polyglycolic acid/polylactic acid (PGA/PLA) scaffold at the final concentration of 5.0 x 10(7)/ml. The cartilage cells and BMSCs were also inoculated separately at the same concentration as the positive and negative control. Pure cartilage cells at 20% of the above mentioned concentration (1.0 x 10(7)/ml) were used as the low concentration cartilage cell control group. Samples were collected 8 weeks later. General observations, wet weight, glycosaminoglycans (GAGs) determination and histological and immunohistochemistry examinations were performed. The expression of type II collagen, type II collagen and aggrecan mRNA were positive in induced BMSCs. In the co-cultured group and the positive control group, pure mature cartilage was formed after 8 weeks of culture in vitro, and the size and shape of the scaffold were maintained. The newly formed cartilage in the two groups were almost the same in appearance and histological properties. The immunohistochemistry results indicated that the cartilage cells of the two groups all expressed ample cartilage-specific type II collagen. The average wet weight and GAG content in the co-cultured group reached more than 70% of those in positive control group. Only an extremely small amount of immature cartilage tissues was formed in local regions in pure BMSC group, and the scaffold was obviously shrunk and deformed. Although the wet weight of newly generated cartilage tissue in the low concentration cartilage cell group reached 30% of that in positive control group, the scaffold was obviously shrunken and deformed. Only regional and discontinuous cartilage tissues were formed, and the amount of newly formed cartilage was obviously less than that in the co-culture group and the positive control group. Chondrocytes can provide a micro-environment for the formation of cartilage, and also effectively induce BMSC to differentiate into chondrocytes and form tissue-engineered cartilage in vitro.