Rabbit Bone Research Articles

Effect of Cissus quadrangularis Hydrogel on Enhancing Osseointegration of Titanium Implant to Bone: An In Vivo Study

The aim of the study was to evaluate the osteogenic potential of Cissus quadrangularis (CQ) hydrogel in enhancing the osseointegration of titanium to the bone in an experimental rabbit model. Six adult male New Zealand white rabbits were used in this study. A total of 24 implants (12 coated test implants and 12 uncoated control implants) were placed in these 6 rabbits. A polyethylene glycol (PEG) hydrogel was prepared with the C. quadrangularis hydrogel in which the test implants were coated. Each rabbit was operated on both hind legs and one implant, each, was placed in the femur and tibia. Hence, one rabbit received four implants [two test implants (HG coated) and two control implants (uncoated)]. The animals were sacrificed after 4 weeks, and the specimens were histomorphometrically analyzed. The bone-to-implant contact (BIC) and the bone area fraction occupancy (BAFO) were calculated using Image J analysis. The statistically analyzed values which were obtained by paired t-test, revealed that the average mean values were higher in the test implants (coated) than the control implants (uncoated). The BIC values of the test implants were not significantly different from the control implants in the case of both femur and tibia (p >0.05). The test implants showed significantly increased BAFO values in femur (p <0.05). However, the BAFO values of test implants in tibia did not vary significantly from the control implants. Based on the findings of the study, the authors conclude that the coating of C. quadrangularis hydrogel enhances the osseointegration of titanium implants to bone. The further studies need to be designed to check the osseointegrative potential of C. quadrangularis. The findings of this study suggest that the C. quadrangularis hydrogel is a potent osteogenic material that can reduce the osseointegration period and thus enhance the patient compliance toward implant treatment.

Conformational Changes in Proteins Caused by High-Pressure Homogenization Promote Nanoparticle Formation in Natural Bone Aqueous Suspension.

As a natural calcium resource, animal bone needs to be miniaturized to the nanoscale to improve palatability and absorption capacity. To explore the mechanism of high-pressure homogenization (HPH) in preparing natural bone aqueous nanosuspensions, the relationships between the changes in protein conformation, solubility and quality characteristics of rabbit bone aqueous suspensions (RBAS) prepared by different HPH cycles were studied. The results showed that the improvements in particle size, stability and calcium solubility of RBASs could be mainly attributed to the improvement of protein solubility induced by the changes in protein conformation. HPH treatment led to the denaturation and degradation of protein in rabbit bone, generating soluble peptides and improving the stability of the suspensions by enhancing the surface charge of the particles. When collagen as the main protein was partially degraded, the hydroxyapatite in the bone was crushed into tiny particles. The increase in the particle-specific surface area led to the release of calcium ions, which chelated with the peptides to produce peptide calcium. However, excessive HPH treatment caused the production of protein macromolecular aggregates and affected the quality of RBASs. This study is helpful to promote the application of HPH technology in animal bone nanoprocessing.

Additive manufactured polyether-ether-ketone composite scaffolds with hydroxyapatite filler and porous structure promoted the integration with soft tissue

Additive Manufactured (AM) Polyether-ether-ketone (PEEK) orthopaedic implants offer new opportunities for bone substitutes. However, owing to its chemical inertness, the integration between PEEK implants and soft tissue represents a major challenge threatening the early success of the PEEK implants. Here we investigated the influence of hydroxyapatite (HA) fillers and porous structure of AM HA/PEEK scaffolds on the integration with soft tissue through in-vitro cellular experiments and in-vivo rabbit experiments. Among the animal experiments, HA/PEEK composite scaffolds with HA contents of 0, 20 wt%, 40 wt% and pore sizes of 0.8 mm, 1.6 mm were manufactured by fused filament fabrication. The results indicated that HA promoted the proliferation and adhesion of myofibroblasts on PEEK-based composites by releasing Ca2+ to active FAK and its downstream proteins, while the surface morphology of the scaffolds was also roughened by the HA particles, both of which led to the tighter adhesion between HA/PEEK scaffolds and soft tissue in-vivo. The macroscopic bonding force between soft tissue and scaffolds was dominated by the pore size of the scaffolds but was hardly affected by neither the HA content and nor the surface morphology. Scaffolds with larger pore size bonded more strongly to the soft tissue, and the maximum bonding force reached to 5.61 ± 2.55 N for 40 wt% HA/PEEK scaffolds with pore size of 1.6 mm, which was higher than that between natural bone and soft tissue of rabbits. Although the larger pore size and higher HA content of the PEEK-based scaffolds facilitated the bonding with the soft tissue, the consequent outcome of reduced mechanical properties has to be compromised in the design of the porous PEEK-based composite implants. The present study provides engineering-accessible synergistic strategies on material components and porous architecture of AM PEEK orthopaedic implants for improving the integration with soft tissue.

TGF-β1 and -β3 for Mesenchymal Stem Cells Chondrogenic Differentiation on Poly (Vinyl Alcohol)-Chitosan-Poly (Ethylene Glycol) Scaffold.

Transforming growth factor-beta 1 (TGF-β1) has been reported to promote chondrogenic differentiation and proliferation in the multipotent stromal cell (MSCs), and the transforming growth factor-beta 3 (TGF-β3) tends to be exclusively in promoting cell differentiation alone. The objective of this study was to determine the effect of TGF-β1 and -β3 on the MSCs chondrogenic differentiation on the poly (vinyl alcohol)-chitosan-poly (ethylene glycol) (PVA-NOCC-PEG) scaffold, compared with that of monolayer and pellet cultures. In this study, P2 rabbit bone marrow-derived MSCs were seeded either on the untreated six-well plate (for monolayer culture) or onto the PVA-NOCC-PEG scaffold or cultured as a pellet culture. The cultures were maintained in a chemically defined serum-free medium supplemented with 10 ng/mL of either TGF-β1 or TGF-β3. Cell viability assay, biochemical assay, and real-time polymerase chain reaction were performed to determine the net effect of cell proliferation and chondrogenic differentiation of each of the growth factors. The results showed that the PVA-NOCC-PEG scaffold enhanced MSCs cell proliferation from day 12 to 30 (p < 0.05); however, no significant differences were observed in the cell proliferation between the cultures supplemented with or without TGF-β1 and TGF-β3 (p > 0.05). In terms of chondrogenic differentiation, the PVA-NOCC-PEG scaffold augmented the GAGs secretion in MSCs and the mRNA expression levels of Sox9, Col2a1, Acan, and Comp were elevated (p < 0.05). However, there was no significant difference between both the TGF-β1 and TGF-β3-treated groups (p > 0.05). In conclusion, TGF-β1 and TGF-β3 enhanced the chondrogenic differentiation of MSCs seeded on the PVA-NOCC-PEG scaffold; however, there was no significant difference between the effect of TGF-β1 and TGF-β3. Impact statement Transforming growth factor-beta (TGF-β) superfamily members is a key requirement for the in vitro chondrogenic differentiation of mesenchymal stem cells (MSCs). In this study, the effects of TGF-β1 and -β3 on MSC chondrogenic differentiation and proliferation on a novel three-dimensional scaffold, the poly(vinyl alcohol)-chitosan-poly(ethylene glycol) (PVA-NOCC-PEG) scaffold, was evaluated. In this study, the results showed both TGF-β1 and TGF-β3 can enhance the chondrogenic differentiation of MSCs seeded on the PVA-NOCC-PEG scaffold.

The Antibacterial Activity Comparison between Novel Carbon-Based Nanofilm Coated Titanium Alloy and Co-Cr-Mo Alloy.

Objective The purpose of this study was to reveal the antibacterial activity of carbon-based nanofilm titanium alloy. Methods The experiments were performed both in vitro and in vivo of animals using two circular-piece test specimens of the same specification, which were made from carbon-based nanofilm coated titanium alloy and commonly used in artificial joints Co-Cr-Mo alloy, respectively. In the in vitro experiments, the two test specimens were cocultured with standard strains of Staphylococcus aureus and Escherichia coli, and the antibacterial properties of the two test specimens were evaluated via inhibition zone size, scanning electron microscopy, fluorescence staining, colony forming unit count, and others; the cytotoxicities of the two test specimens were evaluated by coculturing and them with rabbit bone marrow mesenchymal stem cells (BMSCs). In the in vivo experiments, the two test specimens were implanted in the muscle tissue of experimental rabbits to evaluate their histocompatibilities. Results Both in vitro cocultures of the carbon-based nanofilm titanium alloy and the Co-Cr-Mo alloy with Staphylococcus aureus and Escherichia coli failed to form inhibition zone. However, some biofilms were observed on the surface of the Co-Cr-Mo alloy. Fewer bacteria adhered to the carbon-based nanofilm titanium alloy can be observed via scanning electron microscopy and fluorescence staining techniques. Meanwhile, the colony forming counts showed that, compared with the Co-Cr-Mo alloy, the carbon-based nanofilm titanium alloy had fewer bacteria adhered (P < 0.05). After coculture of the two test specimens with rabbit BMSCs, there was no significant difference in cell count, and both cell counts showed no cytotoxicity. In the in vivo experiment of animals, there are relatively fewer giant cells and better histocompatibility in tissues near the carbon-based nanofilm titanium alloy. Conclusion Compared with Co-Cr-Mo alloy, the novel carbon-based nanofilm titanium alloy enjoys stronger in vitro antibacterial activity and better in vivo histocompatibility.

Effect of chemical modification on physicochemical and biological properties of chondroitin sulfate

Chondroitin sulfate (CS) derivatives are useful biomacromolecules for fabrication of biomaterials. However, chemical modifications of CS molecular structure during processing may alter its physicochemical and biological properties. Here, we studied these changes in molecular and biological functions following CS oxidation to different oxidation. Under ultraviolet visible (UV–Vis) spectroscopy, CS exhibited a blue shift in characteristic absorption peaks after the oxidation. The thermo-stability of the modified CS was also weaker than its original molecular form. Both FTIR and NMR results demonstrated distinct structural changes at the molecular level after oxidation. In vitro study showed that rabbit bone marrow stromal cells cultured with oxidized CS (CSA) containing cell culture medium exhibited viability comparable to normal cell culture medium for CSA concentration less than 125 mg/mL. However, CSA may also inhibit proliferation of these cells. Besides, unmodified CS could induce a chondrogenesis of stem cells, but this function was weakened after chemical modification. Interestingly, chemical modification altered physicochemical and biological properties in substitution degree-dependent manner with the highly oxidized CS exhibiting the lowest stability and chondrogenic induction. These results indicated that chemical modification of biomacromolecules, such as CS, could change both their physicochemical properties and biological functions, suggesting the need to carefully control parameters during biomaterial processing and fabrication.

Spatial quantitation of antibiotics in bone tissue compartments by laser-capture microdissection coupled with UHPLC-tandem mass spectrometry

Bones are the site of multiple diseases requiring chemotherapy, including cancer, arthritis, osteoporosis and infections. Yet limited methodologies are available to investigate the spatial distribution and quantitation of small molecule drugs in bone compartments, due to the difficulty of sectioning undecalcified bones and the interference of decalcification methods with spatially resolved drug quantitation. To measure drug concentrations in distinct anatomical bone regions, we have developed a workflow that enables spatial quantitation of thin undecalcified bone sections by laser-capture microdissection coupled to HPLC/tandem mass spectrometry, and spatial mapping on adjacent sections by mass spectrometry imaging. The adhesive film and staining methods were optimized to facilitate histology staining on the same sections used for mass spectrometry image acquisition, revealing drug accumulation in the underlying bone tissue architecture, for the first time. Absolute spatial concentrations of rifampicin, bedaquiline, doxycycline, vancomycin and several of their active metabolites are shown for both small rodent bones and larger rabbit bones that more closely resemble human bone density. Overlaid MALDI mass spectrometry images of drugs and histology staining enabled the generation of semi-quantitative data from regions of interest within anatomical bone compartments. These data correlated with absolute drug concentrations determined by HPLC–MS/MS in laser-capture microdissection samples. Collectively, these techniques enable semi- and fully quantitative drug distribution investigations within bone tissue compartments for the first time. Our workflow can be translated to image and quantify not only drugs but also biomarkers of disease to investigate drug penetration as well as mechanisms underlying bone disorders.Graphical abstract

An experimental study on the effect of preoperative autologous blood donation on bone marrow hematopoiesis and hematopoietic stem cells.

To evaluate the effect of autologous blood transfusion (ABT) on hematopoietic stem cells through the observation of the changes in the number and activity of bone marrow CD34+ cells after preoperative autologous blood donation (PABD). Rabbit bone marrow specimens were collected preoperatively (T2), 6 h postoperatively (T3), and 24 h postoperatively (T4). Next, the percentages of CD34+ cells, the cell cycle, and the relative expression of telomeric DNA were measured in each group of rabbits. Peripheral blood specimens were collected before PABD (T1) and at T4 to measure reticulocytes. At T3 and T4, the percentages of CD34+ cells and the expressions of telomeric DNA were significantly higher, and the percentages of cells in the G1 phase were significantly lower in each experimental group compared with those in the blank control group (group A) (P<0.05). Compared with the surgical blood collection group (group C), the CD34+ cells and the expressions of telomeric DNA were significantly higher, and the percentages of cells in the G1 phase were significantly lower in the preoperative autologous whole blood group (group D) and the preoperative autologous blood component group (group E) (P<0.05). Compared with group D, the CD34+ cells and the expressions of telomeric DNA were significantly lower, and the percentages of cells in the G1 phase were significantly higher in group E (P<0.05). At T4, the reticulocyte percentages in the surgery group (group B) and group C were significantly higher than in group E and group D, and the reticulocyte percentages in group E were higher than in group D (P<0.05). This study's findings indicated that ABT suppressed bone marrow hematopoiesis, while autologous blood component transfusion had less of an effect than that of whole blood transfusion. Therefore, PABD blood component transfusion would be superior to autologous whole blood transfusion.

Tissue-engineered tendon nano-constructs for repair of chronic rotator cuff tears in large animal models.

Chronic rotator cuff tears (RCTs) are one of the most common injuries of shoulder pain. Despite the recent advances in surgical techniques and improved clinical outcomes of arthroscopically repaired rotator cuffs (RCs), complete functional recovery-without retear-of the RC tendon through tendon-to-bone interface (TBI) regeneration remains a key clinical goal to be achieved. Inspired by the highly organized nanostructured extracellular matrix in RC tendon tissue, we propose herein a tissue-engineered tendon nano-construct (TNC) for RC tendon regeneration. When compared with two currently used strategies (i.e., transosseous sutures and stem cell injections), our nano-construct facilitated more significant healing of all parts of the TBI (i.e., tendon, fibrocartilages, and bone) in both rabbit and pig RCT models owing to its enhancements in cell proliferation and differentiation, protein expression, and growth factor secretion. Overall, our findings demonstrate the high potential of this transplantable tendon nano-construct for clinical repair of chronic RCTs.

Efficiency of Nanohydroxyapatite on Repairing Type II Diabetes Dental Implant-Bone Defect.

The purpose of this study was to see how a nanohydroxyapatite (n-HA) composite polyamide 66 (PA66) affected the repair of bone defects in diabetics with titanium implants, as well as to develop experimental materials for the creation of the interface between bone tissue and titanium implants. Rabbit bone marrow mesenchymal stem cells (MSCs) were isolated using n-HA/PA66 composite material, and the effect of coculture with the material on cell proliferation was analyzed after induction of mineralization. Bone defect models of diabetic experimental rabbits and titanium implants were prepared. Normal rabbits with bone defects were used as control (NC group, N = 8). After the diabetic bone defect (DM group, N = 8) and the implantation of n-HA/PA66 composite material (n-HA/PA66 group, N = 8), the differences in body weight, blood glucose, scanning electron microscopy of the implant-bone interface, bone mineral density, new bone trabecular parameters, histomorphology, and biomechanical properties of the implant-bone interface were compared and analyzed. In vitro test results showed that MSC cell growth could be promoted by mineralization induction, the cell growth condition was good after coculture with n-HA/PA66, and the proliferation activity of MSCs was not affected by the material. In vivo test results showed that the body weight of the DM group and n-HA/PA66 group was considerably inferior to that of the NC group, and the blood glucose was dramatically superior to that of the NC group (P < 0.05). However, the body weight of the n-HA/PA66 group was dramatically superior to that of the DM group (P < 0.05). The bone mineral density, bone volume fraction (BV/TV), bone surface area fraction (BS/BV), bone trabecular thickness (Tb.Th), bone trabecular number (Tb.N), bone trabecular area, and biomechanical properties in the DM group were considerably inferior to those in the NC group and n-HA/PA66 group (P < 0.05). The trabecular space (Tb.Sp) in the NC group and n-HA/PA66 group was dramatically superior to that in the NC group (P < 0.05). The bone mineral density, BV/TV, BS/BV, Tb.Th, Tb.N, trabecular area, and biomechanical properties of the n-HA/PA66 group were dramatically superior to those of the NC group (P < 0.05), while Tb.Sp was considerably inferior to that of the NC group (P < 0.05). These findings showed that the n-HA/PA66 material had good biocompatibility and minimal cytotoxicity, and that filling the space between the surrounding bone and the titanium implant can enhance bone repair. This research paved the way for future research into the tissue-engineered bone in the field of oral surgery.

Acupotomy inhibits aberrant formation of subchondral bone through regulating osteoprotegerin/receptor activator of nuclear factor-κB ligand pathway in rabbits with knee osteoarthritis induced by modified Videman method.

To investigate the effects of acupotomy on inhibiting abnormal formation of subchondral bone in rabbits with knee osteoarthritis (KOA). A total of 24 New Zealand rabbits were randomly divided into four groups of 6 rabbits each [control, model, electroacupuncture (EA) and acupotomy]. Eighteen KOA model rabbits were established using a modified Videman method. Rabbits in EA and acupotomy groups received the intervention for 3 weeks. Then, the cartilage and subchondral bone unit were obtained and the histomorphological changes were recorded. Osteo-protegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) in subchondral bone were evaluated by Western blotting, real-time polymerase chain reaction and immunohistochemistry. Compared with the model group, both the acupotomy and EA groups showed a significant decrease in the Lequesne index (both 0.01) and Mankin score ( 0.01, < 0.05). In addition, both EA and acupotomy groups had a higher expression of total articular cartilage (TAC) ( 0.05, < 0.01) and lower expression of articular calcified cartilage (ACC)/TAC ( 0.05, < 0.05) compared with the model group. The thickness of the subchondral bone plate in EA and acupotomy groups were decreased (both 0.01) compared to the model group. Moreover, trabecular bone volume (BV/TV), protein and relative expression of OPG and the ratio of OPG/RANKL in the subchondral bone of acupotomy group were decreased statistically significant, while these parameters were not significantly changed in the EA group compared with the model group. In the rabbit model of KOA, acupotomy inhibits aberrant formation of subchondral bone by suppressing OPG/RANKL ratio as a potential therapy for KOA.

Icariin promotes the repair of bone marrow mesenchymal stem cells in rabbit knee cartilage defects via the BMP/Smad pathway.

BackgroundIcariin (ICA) has been widely used in the treatment of osteoporosis. However, the potential mechanism of its critical role in repairing knee cartilage damage still needs to be further clarified.MethodsFirst, rabbit bone marrow mesenchymal stem cells (BMSCs) were isolated, cultured, and identified. Subsequently, BMSCs were treated with different concentrations of ICA. Cell Counting Kit 8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) were used to evaluate the cell proliferation in each group. Alcian Blue staining, immunofluorescence, and western blotting were used to evaluate the ability of BMSCs to differentiate cartilage. In addition, a rabbit knee cartilage injury model was established. Evaluation of cartilage defects in each group was performed according to the classification system outlined by the International Cartilage Repair Society (ICRS). Hematoxylin and eosin (HE), Alcian Blue, and immunohistochemistry were used to analyze the pathological status of knee cartilage.ResultsIn vitro, the results showed that ICA promoted the cartilage differentiation of BMSCs as well as cell proliferation. In addition, ICA promoted the expression of type II collagen (COL2A1), aggrecan, and bone morphogenetic protein 2 (BMP2) in BMSCs, while BMP-Smad inhibitor (Noggin) reversed the repair effect of ICA on BMSCs. In vivo, our results showed that the ICRS score of the BMSC and ICA treatment group was higher. Moreover, BMSC and ICA treatment promoted the proliferation of chondrocytes and repaired the cartilage-like tissue on the surface of cartilage defect.ConclusionsThe combined application of ICA and BMSCs can repair rabbit knee cartilage injury by regulating the BMP/Smads pathway, indicating that ICA and BMSCs may be a viable clinical treatment strategy for knee cartilage damage.

Influence of morphofunctional properties of platelets on the mechanical characteristics of the «bone tissue-implant» system in the experiment

The use of platelet-based biological materials attracts special attention in regenerative medicine. The aim of the work was to study the peculiarities of mechanical properties of the system «peri-implant bone tissue-implant» depending on the morphofunctional properties of platelets under conditions of titanium rod implantation into the femur bone of rabbits. The number of platelets, mean volume (MPV), thrombocrit, ratio of large platelets to their total number, and ADP-induced aggregation were determined. During mechanical testing, we determined the maximum load on the «peri-implant bone-implant» system and its elastic properties. According to the result of preoperative determination of the morphofunctional characteristics of the platelets, the rabbits were divided into 2 groups: low platelet potential (LTP) and high platelet potential (HPP). Determination of the mechanical parameters of the «peri-implant bone tissue-implant» system showed that the maximum load in the NTP group was lower than in the VTP group, at the same time, no significant differences were found in the parameter characterizing elasticity (Elastic). The number as well as the morphofunctional characteristics of the circulating platelets in the blood have a significant impact on the strength characteristics of the newly formed peri-implant bone tissue.

Degradation-Kinetics-Controllable and Tissue-Regeneration-Matchable Photocross-linked Alginate Hydrogels for Bone Repair.

Photocross-linked alginate hydrogels, due to their biodegradability, biocompatibility, strong control for gelling kinetics in space and time, and admirable adaptability for in situ polymerization with a minimally invasive approach in surgical procedures, have created great expectations in bone regeneration. However, hydrogels with suitable degradation kinetics that can match the tissue regeneration process have not been designed, which limits their further application in bone tissue engineering. Herein, we finely developed an oxidation strategy for alginate to obtain hydrogels with more suitable degradation rates and comprehensively explored their physical and biological performances in vitro and in vivo to further advance the clinical application for the hydrogels in bone repair. The physical properties of the gels can be tuned via tailoring the degree of alginate oxidation. In particular, in vivo degradation studies showed that the degradation rates of the gels were significantly increased by oxidizing alginate. The activity, proliferation, initial adhesion, and osteogenic differentiation of rat and rabbit bone marrow stromal cells (BMSCs) cultured with/in the hydrogels were explored, and the results demonstrated that the gels possessed excellent biocompatibility and that the encapsulated BMSCs were capable of osteogenic differentiation. Furthermore, in vivo implantation of rabbit BMSC-loaded gels into tibial plateau defects of rabbits demonstrated the feasibility of hydrogels with appropriate degradation rates for bone repair. This study indicated that hydrogels with increasingly controllable and matchable degradation kinetics and satisfactory bioproperties demonstrate great clinical potential in bone tissue engineering and regenerative medicine and could also provide references for drug/growth-factor delivery therapeutic strategies for diseases requiring specific drug/growth-factor durations of action.

Multiscale Hierarchical Architecture-Based Bioactive Scaffolds for Versatile Tissue Engineering.

Artificial construction from tendon to bone remains a formidable challenge in tissue engineering owing to their structural complexity. In this work, bioinspired calcium silicate nanowires and alginate composite hydrogels are utilized as building blocks to construct multiscale hierarchical bioactive scaffolds for versatile tissue engineering from tendon to bone. By integrating 3D printing technology and mechanical stretch post-treatment in a confined condition, the obtained composite hydrogels possess bioinspired reinforcement architectures from nano- to submicron- to microscale with significantly enhanced mechanical properties. The biochemical and topographical cues of the composite hydrogel scaffolds provide much more efficient microenvironment to the rabbit bone mesenchymal stem cells and rabbit tendon stem cells, leading to ordered alignment and improved differentiation. The composite hydrogels markedly promote in vivo tissue regeneration from bone to tendon, especially fibrocartilage transitional tissue. Therefore, such calcium silicate nanowires/alginate composite hydrogels with multiscale hierarchical structures have potential application for tissue regeneration from tendon to bone. This work provides an innovative strategy to construct multiscale hierarchical architecture-based scaffolds for tendon/bone engineering.

3D-Printed Double-Helical Biodegradable Iron Suture Anchor: A Rabbit Rotator Cuff Tear Model.

Suture anchors are extensively used in rotator cuff tear surgery. With the advancement of three-dimensional printing technology, biodegradable metal has been developed for orthopedic applications. This study adopted three-dimensional-printed biodegradable Fe suture anchors with double-helical threads and commercialized non-vented screw-type Ti suture anchors with a tapered tip in the experimental and control groups, respectively. The in vitro study showed that the Fe and Ti suture anchors exhibited a similar ultimate failure load in 20-pound-per-cubic-foot polyurethane foam blocks and rabbit bone. In static immersion tests, the corrosion rate of Fe suture anchors was 0.049 ± 0.002 mm/year. The in vivo study was performed on New Zealand white rabbits and SAs were employed to reattach the ruptured supraspinatus tendon. The in vivo ultimate failure load of the Fe suture anchors was superior to that of the Ti suture anchors at 6 weeks. Micro-computed tomography showed that the bone volume fraction and bone surface density in the Fe suture anchors group 2 and 6 weeks after surgery were superior, and the histology confirmed that the increased bone volume around the anchor was attributable to mineralized osteocytes. The three-dimensional-printed Fe suture anchors outperformed the currently used Ti suture anchors.

Three-dimensional-printed polycaprolactone scaffolds with interconnected hollow-pipe structures for enhanced bone regeneration.

Three-dimensional (3D)-printed scaffolds are widely used in tissue engineering to help regenerate critical-sized bone defects. However, conventional scaffolds possess relatively simple porous structures that limit the delivery of oxygen and nutrients to cells, leading to insufficient bone regeneration. Accordingly, in the present study, perfusable and permeable polycaprolactone scaffolds with highly interconnected hollow-pipe structures that mimic natural micro-vascular networks are prepared by an indirect one-pot 3D-printing method. In vitro experiments demonstrate that hollow-pipe-structured (HPS) scaffolds promote cell attachment, proliferation, osteogenesis and angiogenesis compared to the normal non-hollow-pipe-structured scaffolds. Furthermore, in vivo studies reveal that HPS scaffolds enhance bone regeneration and vascularization in rabbit bone defects, as observed at 8 and 12 weeks, respectively. Thus, the fabricated HPS scaffolds are promising candidates for the repair of critical-sized bone defects.

Keeping the periodontium youthful: truth or myth? Strategy and tactical approaches in periodontology based on preventive, predictive, personalized medicine

Relevance. The use of osteoplastic materials and hyaluronic acid in periodontology is extremely important for modern dentistry, since the predictive introduction of an osteoinductive drug and / or hyaluronic acid into the treatment protocol will allow simulating a state close to physiological, rejuvenating, and achieving the results of maximum restoration of periodontal structures.Aim. To experimentally confirm the possibility of maintaining the physiological state and rejuvenating the periodontium using osteoplastic materials and / or hyaluronic acid.Materials and methods. During the experiment, the dynamics of reparative osteogenesis in artificially reproduced defects of the jaw bones in rabbits was studied with the use of osteoplastic materials "Klipdent", "Bioplast-dent" or without the use of regeneration stimulants, as well as the morphogenesis of periodontal tissues when using hyaluronic acid. Results: the morphological studies carried out may indicate the acceleration of the regeneration processes in comparison with the normal course for 6-7 days.Conclusions. It has been experimentally proven that the preservation and prolongation of periodontal youth is possible. We consider it appropriate and important in the conditions of modern dentistry, provided that the correct clinical strategy and tactical methods are chosen. In particular, the improvement of the procedure for open curettage of the periodontal pocket by predictively introducing an osteoinductive drug and / or hyaluronic acid into the treatment protocol will significantly increase the effectiveness of therapeutic measures and restore the periodontal condition close to physiological.

Osteochondral regeneration in rabbit using xenograft decellularized ECM in combination with different biological products; platelet-rich fibrin, amniotic membrane extract, and mesenchymal stromal cells.

This study aimed to investigate the regenerative effect of decellularized osteochondral ECM xenograft in combination with various biological products in an osteochondral (OC) defect. OC tissue from the sheep femur were obtained and decellularized. The decellularized ECM (dECM) was combined with either platelet-rich fibrin (PRF), amniotic membrane extract (AME), or rabbit bone marrow-derived mesenchymal stromal cells (rBMSCs). The hybrid dECM-biological products were then utilized for the treatment of rabbit OC critical size defects. The regenerative potential of different groups was compared using; MRI, macroscopic assessment, histopathology, and histomorphometry. All characterizations analysis verified successful decellularization. Three months post-surgery, macroscopic findings indicated that dECM was better compared to controls. Also, dECM in combination with AME, PRF, and rBMSCs showed enhanced OC regeneration compared to only dECM (AME: +100%, PRF: +61%, rBMSCs: +28%). In particular, the dECM+AME group results in the best integration of new cartilage into surrounding cartilage tissue. The histomorphometric evaluations demonstrated enhancement in new cartilage formation and bone tissue (86.5± 5.9% and 90 ± 7.7%, respectively) for the dECM+AME group compared to other groups. Furthermore, histological results for the dECM+AME elucidated a mature hyaline cartilage tissue that covered the new and symmetrically formed subchondral bone, exhibiting a significantly higher regenerative effect compared to all other treated groups. This finding was also confirmed with MRI images. The current study revealed that in addition to the benefits of dECM alone, its combination with AME indicated to have a superior regenerative effect on OC regeneration. Overall, dECM+AME may be considered a suitable construct for treating knee OC injuries.

Comparison of Stemness and Immunogenicity of Osteo-Differentiated Mesenchymal Stem Cells Derived from Rabbit Bone Marrow and Wharton’s Jelly (Journal of Biomaterials and Tissue Engineering, Vol. 7(12), pp. 1326–1335 (2017))

Comparison of Stemness and Immunogenicity of Osteo-Differentiated Mesenchymal Stem Cells Derived from Rabbit Bone Marrow and Wharton’s Jelly (Journal of Biomaterials and Tissue Engineering, Vol. 7(12), pp. 1326–1335 (2017))