Weeks Of Implantation Research Articles

The effect of medical biodegradable magnesium alloy in vivo degradation and bone response in a rat femur model with long-term fixation.

It is of great significance to understand the effect of the different corrosion behaviors of magnesium (Mg) alloys manufactured using different casting methods and implanted with different methods on the long-term implantation to expand the application of Mg-based biomedical implants. The effects of four different casting and rolling speeds on the microstructure of an Mg-rare earth (Mg-Re) alloy were analyzed using electron backscatter diffraction (EBSD). Four Mg alloys were obtained using vertical two-roll casting (TRC) at 10m/min, 16m/min, 24m/min, and 30m/min, and their microstructure, corrosion behavior and bone reaction in vivo were studied. The corrosion resistance of the alloy increases with an increase in casting speed and finer grain size of the cast-rolled parts. The Mg-Re alloys with TRC-10m/min and TRC-30m/min were selected for animal experiments. The two Mg alloys were made into metal rods and inserted into the rat femur to simulate the effect of Mg-Re on femoral healing under an injury condition. The rods were implanted for a long time to judge the effects of the Mg-Re alloy on the body. The TRC-30m/min implants obtained highly mature new bone tissue in the case of bone injury. The in vivo experiments showed that the corrosion resistance of the TRC-30m/min implant was better than that of the TRC-10m/min implant. After 32 weeks of implantation, there were no pathological changes in the liver, heart, or kidney of rats in the TRC-30m/min group, and the cell structure was normal.

Evaluation of the osteoconductivity and the degradation of novel hydroxyapatite/polyurethane combined with mesoporous silica microspheres in a rabbit osteomyelitis model.

Bone defects caused by osteomyelitis can lead to severe disability. Surgeons still face significant challenges in treating bone defects. Nano-hydroxyapatite (n-HA) plays an important role in bone tissue engineering due to its excellent biocompatibility and osteoconductivity. Levofloxacin (Levo) was encapsulated in mesoporous silica nanoparticles (MSNs) via electrostatic attraction to serve as a drug delivery system. MSNs were incorporated with n-HA and polyurethane (PU). The degradation and osteoconductivity properties of these novel composite scaffolds and their effectiveness in treating chronic osteomyelitis in a rabbit model were assessed. Gross pathology, radiographic imaging, micro-computed tomography, Van Gieson staining, and hematoxylin and eosin staining were conducted at 6 and 12 weeks. The group of composite scaffolds combining n-HA/PU with MSNs containing 5 mg Levo (n-HA/PU + Nano +5 mg Levo) composite scaffolds showed superior antibacterial properties compared to the other groups. At 12 weeks, the n-HA/PU + Nano +5 mg Levo composite scaffolds group exhibited significantly greater volume of new trabecular bone formation compared to the other three groups. The surface of the novel composite scaffolds exhibited degradation after 6 weeks implantation. The internal structure of the scaffolds collapsed noticeably after 12 weeks of implantation. The rate of material degradation corresponded to the rate of new bone ingrowth. This novel composite scaffold, which is biodegradable and osteoconductive, has potential as a drug delivery system for treating chronic osteomyelitis accompanied by bone defects.

Degradation behavior of ZE21C magnesium alloy suture anchors and their effect on ligament-bone junction repair.

Current materials comprising suture anchors used to reconstruct ligament-bone junctions still have limitation in biocompatibility, degradability or mechanical properties. Magnesium alloys are potential bone implant materials, and Mg2+ has been shown to promote ligament-bone healing. Here, we used Mg-2 wt.% Zn-0.5wt.% Y-1wt.% Nd-0.5wt.% Zr (ZE21C) alloy and Ti6Al4V (TC4) alloy to prepare suture anchors to reconstruct the patellar ligament-tibia in SD rats. We studied the degradation behavior of the ZE21C suture anchor via in vitro and in vivo experiments and assessed its reparative effect on the ligament-bone junction. In vitro, the ZE21C suture anchor degraded gradually, and calcium and phosphorus products accumulated on its surface during degradation. In vivo, the ZE21C suture anchor could maintain its mechanical integrity within 12 weeks of implantation in rats. The tail of the ZE21C suture anchor in high stress concentration degraded rapidly during the early implantation stage (0-4weeks), while bone healing accelerated the degradation of the anchor head in the late implantation stage (4-12weeks). Radiological, histological, and biomechanical assays indicated that the ZE21C suture anchor promoted bone healing above the suture anchor and fibrocartilaginous interface regeneration in the ligament-bone junction, leading to better biomechanical strength than the TC4 group. Hence, this study provides a basis for further research on the clinical application of degradable magnesium alloy suture anchors.

A Double Cross-Linked Injectable Hydrogel Derived from Muscular Decellularized Matrix Promotes Myoblast Proliferation and Myogenic Differentiation.

Injectable hydrogels possess tremendous merits for use in muscle regeneration; however, they still lack intrinsic biological cues (such as the proliferation and differentiation of myogenic cells), thus considerably restricting their potential for therapeutic use. Herein, we developed a double cross-linked injectable hydrogel composed of methacrylamidated oxidized hyaluronic acid (MOHA) and muscular decellularized matrix (MDM). The chemical composition of the hydrogel was confirmed using 1H NMR and Fourier transform infrared spectroscopy. To achieve cross-linking, the aldehyde groups in MOHA were initially reacted with the amino groups in MDM through a Schiff-based reaction. This relatively weak cross-linking provided the MOHA/MDM hydrogel with satisfactory injectability. Furthermore, the methacrylation of MOHA facilitated a second cross-linking mechanism via UV irradiation, resulting in improved gelation ability, biomechanical properties, and swelling performance. When C2C12 myogenic cells were loaded into the hydrogel, our results showed that the addition of MDM significantly enhanced myoblast proliferation compared to the MOHA hydrogel, as demonstrated by live/dead staining and Cell Counting Kit-8 assay after seven days of in vitro cultivation. In addition, gene expression analysis using quantitative polymerase chain reaction indicated that the MOHA/MDM hydrogel promoted myogenic differentiation of C2C12 cells more effectively than the MOHA hydrogel, as evidenced by elevated expression levels of myogenin, troponin T, and MHC in the MOHA/MDM hydrogel group. Moreover, after four to eight weeks of implantation in a full-thickness abdominal wall-defect model, the MOHA/MDM hydrogel could promote the reconstruction and repair of functional skeletal muscle tissue with enhanced tetanic force and tensile strength. This study provides a new double cross-linked injectable hydrogel for use in muscular tissue engineering.

Novel hybrid biocomposites for tendon grafts: The addition of silk to polydioxanone and poly(lactide-co-caprolactone) enhances material properties, in vitro and in vivo biocompatibility.

Biopolymers play a critical role as scaffolds used in tendon and ligament (TL) regeneration. Although advanced biopolymer materials have been proposed with optimised mechanical properties, biocompatibility, degradation, and processability, it is still challenging to find the right balance between these properties. Here, we aim to develop novel hybrid biocomposites based on poly(p-dioxanone) (PDO), poly(lactide-co-caprolactone) (LCL) and silk to produce high-performance grafts suitable for TL tissue repair. Biocomposites containing 1-15% of silk were studied through a range of characterisation techniques. We then explored biocompatibility through in vitro and in vivo studies using a mouse model. We found that adding up to 5% silk increases the tensile properties, degradation rate and miscibility between PDO and LCL phases without agglomeration of silk inside the composites. Furthermore, addition of silk increases surface roughness and hydrophilicity. In vitro experiments show that the silk improved attachment of tendon-derived stem cells and proliferation over 72h, while in vivo studies indicate that the silk can reduce the expression of pro-inflammatory cytokines after six weeks of implantation. Finally, we selected a promising biocomposite and created a prototype TL graft based on extruded fibres. We found that the tensile properties of both individual fibres and braided grafts could be suitable for anterior cruciate ligament (ACL) repair applications.

A reduced graphene oxide functionalized electrospun nerve wrap: Amalgamating electrical and biochemical cues to enhance nerve regeneration in median nerve injury model

Nerve injuries leads to severe impairment of target tissue and standard treatment approaches from surgery to electrical stimulation are complex, yielding only brief relief. The current study addresses such limitations with reduced graphene oxide (rGO) functionalized “Electroband”. We attempt to conjugate electrical cues in the nerve wrap with in-situ electrical stimulation in a median nerve injury model in rats, underlining the significance of combinatorial therapy for nerve regeneration. “Electroband” targets three critical aspect of nerve regeneration: neuroprotection, neuroregeneration and neuroplasticity at single stroke. The nanofibrous extracellular matrix mimicking nature of “Electroband” assisted in reconciling the injured niche by preventing anoikis, exerting neuroprotective effect as depicted with aligned growth of compressed nerve fibers. The rGO functionalization coupled with intraoperative electrical stimulation of 3 V @ 20 Hz for 10 min aided in propelling the injured nerve to denervated target, prompting fascicular growth of nerve fibers, targeting neuroplasticity. The nerve growth factor incorporation enhanced the bioactivity of scaffold, augmenting regeneration leading to exuberant growth and myelination of nascent nerve tracts. These results led to significant improvement in electrophysiological recordings with 30–32 mV CMAP value (80% recovery) in combinatorial therapy group as compared to 10–11 mV in negative controls and 13–15 mV in animals with individual therapy. We therefore, report 80% regain in muscular strength within 8 weeks of implantation with combinatorial therapy as assessed with behavioural paw gripping and scratch tape assay. Thus, we successfully demonstrated the pre-clinical efficacy of “Electroband”, reducing the time and frequency of electrical stimulation currently in clinical practice.

P-804 Endometrial recovery via implantable CD133+ stem cells scaffold in Asherman’s syndrome therapy

Abstract Study question Can we use CD133+ bone marrow derived stem cell (BMDSCs) loaded scaffolds to aid endometrial regeneration locally in Asherman syndrome (AS)? Summary answer Gelatin scaffolds supported transdifferentiation via decidualization of CD133+ BMDSCs. Implantable CD133+ scaffolds showed a certain degree of endometrial recovery in an AS rat model. What is known already We have demonstrated that CD133+ BMDSCs contribute to endometrial proliferation, and functional recovery in murine models of AS (Cervelló et al., 2015) and humans (Santamaria et al., 2016). This advanced cell therapy is already in Phase II Clinical trial regulated by EMA. Here, we use bioengineered loaded-cell scaffolds to obtain a more localized cell therapy. Study design, size, duration Gelatin scaffolds were prepared by cryogelation and analyzed by micro-computed tomography. For in vitro studies, CD133+ were cultured into the scaffolds and decidualized with 1 mM of 8-Bromoadenosine 3´5´-cyclic monophosphate sodium salt (cAMP) for 7 days. For studies in vivo, the scaffolds used as the control group (gelatin scaffold only) and the CD133+ loaded gelatin scaffolds were implanted into acid-damaged horns of rat AS induced model followed after one and three weeks. Participants/materials, setting, methods DNA quantification was carried out for cell viability on the scaffolds, whereas immunofluorescence, single cell RNA sequencing and RT-qPCR were used to assess decidualization. For studies in vivo, endometrial recovery was screened by scanning electron microscopy (SEM), hematoxylin and eosin staining (H&E) and RT-qPCR. Main results and the role of chance Cell spreading and proliferation was observed in gelatin loaded scaffolds due to its high pore size and similarity to the native extracellular matrix. IGFBP1 and Prolactin expression determined by immunofluorescence and RT-qPCR demonstrated that gelatin scaffold supported decidualization of CD133 into stromal decidual cells. Additionally, single cell data revealed a higher expression of stromal specific canonical markers (ENG, CXCL12, PDGFRB) and decidual associated genes (IRS2, COCH) in the decidualized scaffold. During the in vivo studies of the implanted scaffolds in a rat model of AS, we studied a set of inflammatory genes and paracrine secretory molecules. For the CD133+ loaded gelatin scaffold, we obtained a decrease in the expression of NF-kB (p ≤ 0.01). Additionally, the number of glands as well as endometrial thickness showed an increasing trend for the bioengineered cell loaded scaffolds after 3 weeks of implantation. Limitations, reasons for caution Endometrial functionality should be further analysed to needed full endometrial recovery. Wider implications of the findings Our bioengineered scaffolds mimic the native extracellular matrix, contributing to the viability, proliferation and decidualization of CD133+ BMDSCs. The herein implanted CD133+ BMDSCs scaffolds open new avenues to localized cell therapy for endometrial regeneration, especially for AS patients. Trial registration number Not applicable

The Safe Use of 125I-Seeds as a Localization Technique in Breast Cancer during Pregnancy

Introduction: Some aspects of the treatment protocol for breast cancer during pregnancy (PrBC) have not been thoroughly studied. This study provides clarity regarding the safety of the use of 125I-seeds as a localization technique for breast-conserving surgery in patients with PrBC. Methods: To calculate the exposure to the fetus of one 125I-seed implanted in a breast tumor, we developed a model accounting for the decaying 125I-source, time to surgery, and the declining distance between the 125I-seed and the fetus. The primary outcome was the maximum cumulative fetal dose of radiation at consecutive gestational ages (GA). Results: The cumulative fetal dose remains below 1 mSv if a single 125I-seed is implanted at a GA of 26 weeks. After a GA of 26 weeks, the fetal dose can be at a maximum of 11.6 mSv. If surgery takes place within two weeks of implantation from a GA of 26 weeks, and one week above a GA of 32 weeks, the dose remains below 1 mSv. Conclusion: The use of 125I-seeds is safe in PrBC. The maximum fetal exposure remains well below the threshold of 100 mSv, and therefore, does not lead to an increased risk of fetal tissue damage. Still, we propose keeping the fetal dose as low as possible, preferably below 1 mSv.

Bioactive impact of manuka honey and bone char incorporated into gelatin and chitosan cryogels in a rat calvarial fracture model.

Bone tissue engineered scaffolds are designed to mimic the natural environment for regeneration when typical healing is inhibited. Autografts are the current gold standard for treatment but are limited by available bone and supplementary surgical sites that broaden complications and comorbidities. Cryogels are an ideal scaffold in bone regeneration due to their mechanical integrity and marcoporous structure that elicits angiogenesis and subsequently new bone tissue formation. To aid in bioactivity and osteoinductivity, manuka honey (MH) and bone char (BC) were added to gelatin and chitosan cryogels (CG). Manuka honey has powerful antimicrobial properties to aid against graft infection, and bone char is composed of 90% hydroxyapatite, a well-studied bioactive material. These additives are natural, abundant, easy to use, and cost effective. CG cryogels incorporated with either BC or MH, and plain CG cryogels were implanted into rat calvarial fracture models for cortical bone regeneration analysis. We found indication of bioactivity with both bone char and manuka honey through the presence of woven bone structure in histology stains and micro computed tomography (microCT) data. Overall, plain CG cryogels supported greater bone regeneration capabilities than the BC or MH incorporated cryogels due to a lack of advanced organized tissue formation and collagen deposition after 8 weeks of implantation; however, future work should explore varying additive concentrations and delivery methods to further assess additive potential.

Lateral Bone Augmentation Using a Three-Dimensional-Printed Polymeric Chamber to Compare Biomaterials.

The aim of this study was to test the suitability of calcium phosphate cement mixed with poly(lactic-co-glycolic acid) (CPC-PLGA) microparticles into a ring-shaped polymeric space-maintaining device as bone graft material for lateral bone augmentation. Therefore, the bone chambers were installed on the lateral portion of the anterior region of the mandibular body of mini-pigs. Chambers were filled with either CPC-PLGA or BioOss® particles for comparison and left for 4 and 12 weeks. Histology and histomorphometry were used to obtain temporal insight in material degradation and bone formation. Results indicated that between 4 and 12 weeks of implantation, a significant degradation of the CPC-PLGA (from 75.1% to 23.1%), as well as BioOss material, occurred (from 40.6% to 14.4%). Degradation of both materials was associated with the presence of macrophage-like and osteoclast-like cells. Furthermore, a significant increase in bone formation occurred between 4 and 12 weeks for the CPC-PLGA (from 0.1% to 7.2%), as well as BioOss material (from 8.3% to 23.3%). Statistical analysis showed that bone formation had progressed significantly better using BioOss compared to CPC-PLGA (p < 0.05). In conclusion, this mini-pig study showed that CPC-PLGA does not stimulate lateral bone augmentation using a bone chamber device. Both treatments failed to achieve "clinically" meaningful alveolar ridge augmentation.

Three‐dimensional starch‐based scaffold decorated with 64S bio‐glass for accelerating rat model bone defect repair

AbstractStarch (ST)‐based scaffold consists of aloe vera (AV) and 64S bioactive glass (BG) reinforced with quail egg shell powder (QE) was successfully fabricated through freeze‐drying technique. Scaffolds revealed antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria, forming inhibition zones of 12.64–16.23 mm. Collagen I and Runt‐related transcription factor 2 expressions as early‐stage osteogenic differentiation markers were reported to be in the ranges of 34.11% ± 1.46% to 69.47% ± 1.64% and 34.31% ± 2.43% to 71.47% ± .94%, respectively. Moreover, the in vivo expression of osteopontin after 4 weeks of implantation was 25.39% ± 2.92%/500 μm for the blank group and 56.68% ± 4.09%/500 μm for the scaffold group, respectively. Moreover, new bone formation and proliferation of collagen fibers were observed in the scaffold group. Obtained results revealed that AV incorporated ST‐BG‐QE scaffold can be considered a promising candidate for bone tissue repair.

PO-04-017 'LEFT' BROKEN AFTER EXERCISE: A CASE OF PAINFUL LBBB SYNDROME SUCCESSFULLY TREATED WITH LEFT BUNDLE BRANCH AREA PACING

The leading causes of new-onset left bundle branch block (LBBB) include coronary artery disease, hypertension, and cardiomyopathies. However, when the LBBB occurs in the absence of ischemia, in a rate-dependent manner, usually with exertion, it constitutes a painful left bundle branch block. Although there are multiple case reports of this entity, the mechanism, pathophysiology, and treatment are not well defined. We intend to raise awareness of this syndrome and highlight our unique treatment approach. NA A 57-year-old male presented to the cardiology clinic with exertional chest pain and palpitations. He underwent an exercise ECG test, surprisingly on stage 2 of Bruce protocol, at around a heart rate of 116 bpm; he started developing LBBB on every other beat. At a heart rate of 125 bpm, he developed persistent LBBB associated with similar symptoms, both of which persisted in the recovery phase (Figure 1). His Echocardiogram was normal. Invasive coronary angiography revealed normal coronaries. Previous case reports have shown that cardiac rehabilitation helps to delay the onset of LBBB to a higher heart rate; however, he opted for pacemaker implantation as he had severe exercise limitations. He underwent a biventricular-implantable pacemaker with right atrial, left bundle branch area, and coronary sinus (CS) left ventricular (LV) leads. The pacemaker was programmed DDD60 with a rate adaptive AV interval with a start rate of 80 bpm. This would enable the LBB area pacing above a heart rate of 80 bpm. Within one week of implantation, the patient had a complete resolution of his symptoms. A cardiopulmonary exercise test to assess VO2 with pacing programmed off and then on is scheduled as part of the follow-up. The symptoms of the painful LBBB syndrome can be quite severe, resulting in physical and psychological debilitation. Treatment with a physical exercise regimen has been successful as it delays the LBBB onset to a higher heart rate. However, the patient loses the benefit once they stop exercising. A definitive solution is a pacemaker; there are multiple case reports of His bundle and right ventricular pacing, which successfully treated this syndrome. In this case, we used a unique approach of pacing just the LBBB area; in addition, a CS LV lead was placed, which could be used for an earlier activation of the LV if the patient needs that in the future.

Multi-leveled Nanosilicate Implants Can Facilitate Near-Perfect Bone Healing.

Several studies have shown that nanosilicate-reinforced scaffolds are suitable for bone regeneration. However, hydrogels are inherently too soft for load-bearing bone defects of critical sizes, and hard scaffolds typically do not provide a suitable three-dimensional (3D) microenvironment for cells to thrive, grow, and differentiate naturally. In this study, we bypass these long-standing challenges by fabricating a cell-free multi-level implant consisting of a porous and hard bone-like framework capable of providing load-bearing support and a softer native-like phase that has been reinforced with nanosilicates. The system was tested with rat bone marrow mesenchymal stem cells in vitro and as a cell-free system in a critical-sized rat bone defect. Overall, our combinatorial and multi-level implant design displayed remarkable osteoconductivity in vitro without differentiation factors, expressing significant levels of osteogenic markers compared to unmodified groups. Moreover, after 8 weeks of implantation, histological and immunohistochemical assays indicated that the cell-free scaffolds enhanced bone repair up to approximately 84% following a near-complete defect healing. Overall, our results suggest that the proposed nanosilicate bioceramic implant could herald a new age in the field of orthopedics.

Maturation of Nephrons by Implanting hPSC-derived Kidney Progenitors Under Kidney Capsules of Unilaterally Nephrectomized Mice.

Human pluripotent stem cell (hPSC)-derived kidney organoids may contribute to disease modeling and the generation of kidney replacement tissues. However, the realization of such applications requires the induction of hPSCs into functional mature organoids. One of the key questions for this process is whether a specific vascular system exists for nephrogenesis. Our previous study showed that short-term (2 weeks) implantation of hPSC-derived organoids below the kidney capsules of unilaterally nephrectomized and immunodeficient mice resulted in the enlargement of organoids and production of vascular cells, although signs of maturation were lacking. Organoids were induced for 15 days in vitro and then grafted below kidney capsules of the same unilaterally nephrectomized immunodeficient mouse model to examine whether medium-term (4 weeks) implantation could improve organoid maturation and vascularization, as evaluated by immunofluorescence and transmission electron microscopy. We demonstrated that after 2-4 weeks of implantation, renal organoids formed host-derived vascularization and matured without any exogenous vascular endothelial growth factor. Glomerular filtration barrier maturation was evidenced by glomerular basement membrane deposition, perforated glomerular endothelial cell development, and apical, basal podocyte polarization. A polarized monolayer epithelium and extensive brush border were also observed for tubular epithelial cells. Our results indicate that the in vivo microenvironment is important for the maturation of human kidney organoids. Stromal expansion and a reduction of nephron structures were observed following longer-term (12 weeks) implantation, suggesting effects on off-target cells during the induction process. Accordingly, induction efficiency and transplantation models should be improved in the future.

Effects of Interferon-γ and Interleukin-4 on Proliferating Cell Nuclear Antigen Expression in Transplanted Bone Tumor Tissue

The rabbit VX2 bone tumor model is an ideal animal model for studying malignant bone tumors. Cytokines have been reported to play a role in tumor initiation and promotion, angiogenesis, and metastasis. However, few studies have investigated the relationship between cytokines and VX2 bone tumor development. This study investigated the effect of interferon-γ (IFN-γ) and interleukin-4 (IL-4) on proliferating cell nuclear antigen (PCNA) expression in tumor tissue. Thirty Japanese white rabbits were randomly divided into group A (n = 15) and group B (n = 15). The rabbit VX2 bone tumor model was constructed by implanting VX2 tumors on the medial side of the upper tibia. Group A was sacrificed in the first week of implantation, and group B in the second week of implantation. Peripheral venous blood, tumor tissue from the medullary cavity at the implantation site, and surrounding bone and soft tissue were harvested before implantation and execution in both experimental groups. IFN-γ and IL-4 expression levels in peripheral blood and PCNA levels in tumor tissues were measured by enzyme-linked immunosorbent assay (ELISA). The tumor tissue of the medullary cavity and surrounding bone and soft tissue was harvested for pathological examination. By the end of the experiment, 30 rabbits were included in the study. There was no significant difference in IFN-γ, IL-4 and PCNA expression levels in group A compared to group B before implantation (t = 1.187, p value = 0.255; t = 1.282, p value = 0.221; t = 0.499, p value = 0.626). IFN-γ and IL-4 expression levels before execution in group A were not significantly different from those before implantation (t = -1.280, p value = 0.213; t = 0.952, p value = 0.349), and PCNA expression levels were higher than those before implantation (t = 2.469, p value = 0.020). Group B had significantly lower IFN-γ expression levels before execution than before implantation (t = -3.741, p value = 0.001) and significantly higher IL-4 and PCNA expression levels before execution than before implantation (t = 6.279, p value < 0.01; t = 13.031, p value < 0.001). IFN-γ expression levels before execution in group B was significantly lower than those before execution in group A (t = 17.184, p value < 0.001), and IL-4 and PCNA expression before execution in group B was significantly higher than that before execution in group A (t = -26.235, p value < 0.001; t = -24.619, p value < 0.001). The correlation between IFN-γ and PCNA levels before execution in groups A and B was negative (r = -0.566, p value = 0.028; r = -0.604, p value = 0.017), and the correlation between IL-4 and PCNA levels was positive (r = 0.583, p value = 0.023; r = 0.884, p value < 0.001). In the rabbit VX2 bone tumor model, extending the period of time after tumor implantation resulted in a negative correlation between IFN-γ and PCNA levels and a positive correlation between IL-4 and PCNA levels.

Functional neurological restoration of amputated peripheral nerve using biohybrid regenerative bioelectronics.

The development of neural interfaces with superior biocompatibility and improved tissue integration is vital for treating and restoring neurological functions in the nervous system. A critical factor is to increase the resolution for mapping neuronal inputs onto implants. For this purpose, we have developed a new category of neural interface comprising induced pluripotent stem cell (iPSC)-derived myocytes as biological targets for peripheral nerve inputs that are grafted onto a flexible electrode arrays. We show long-term survival and functional integration of a biohybrid device carrying human iPSC-derived cells with the forearm nerve bundle of freely moving rats, following 4 weeks of implantation. By improving the tissue-electronics interface with an intermediate cell layer, we have demonstrated enhanced resolution and electrical recording in vivo as a first step toward restorative therapies using regenerative bioelectronics.

Irrigating degradation properties of silk fibroin–collagen type II composite cartilage scaffold in vitro and in vivo

Silk fibroin-collagen type II scaffolds are promising in cartilage tissue engineering due to their suitable biological functionality to promote proliferation of chondrocytes in vitro. However, their degradation properties, which are of crucial importance as scaffold degradation should consistent with the new tissue formation process, are still unknown. In this study, degradability of silk fibroin-collagen type II cartilage scaffolds was probed both in vitro and in vivo. In vitro degradation experiments show that the scaffolds decreased 32.25 % ± 0.62 %, 34.27 % ± 0.96 %, 36.27 % ± 2.39 % in weight after 8 weeks of degradation at the irrigation velocity of 0 mL/min, 7.89 mL/min and 15.79 mL/min. The degradation ratio, which increases with time and increasing irrigation velocity, is described by combining the built mathematic model and finite element modeling method. The scaffolds after 8 weeks of degradation in vitro keep their mechanical structural integrity to support new tissues. In vivo degradation experiments conducted in rabbits further show that the scaffolds degrade gradually, be absorbed with time and finally collapse in structure. The degradation process is accompanied by the growth of fibrous tissues and the scaffold is filled by fibrous tissues after 12 weeks of implantation. Immunohistology analysis shows that the inflammation caused by scaffolds is controllable and gradually alleviates with time. To sum up, silk fibroin-collagen type II cartilage scaffolds, which show suitable mechanical properties and biocompatibility during degradation in vitro and in vivo, have great potential in cartilage repair. The novelty of the study is that it not only introduces a mathematical model to predict the irrigation degradation ratio, but also provides experimental degradation data support for clinical application of silk fibroin-collagen type II cartilage scaffolds.

Integrated and Bifunctional Bilayer 3D Printing Scaffold for Osteochondral Defect Repair

AbstractBioinspired scaffolds with two distinct regions resembling stratified anatomical architecture provide potential strategies for osteochondral defect repair and are studied in preclinical animals. However, delamination of the two layers often causes tissue disjunction between the regenerated cartilage and subchondral bone, leading to few commercially available clinical applications. This study develops an integrated poly(ε‐caprolactone) (PCL)‐based scaffold for repairing osteochondral defects. An extracellular matrix (ECM)‐incorporated 3D printing composite scaffold (ECM/PCL) coated with ECM hydrogel (E‐co‐E/PCL) is fabricated as the upper layer, and magnesium oxide nanoparticles coated with polydopamine (MgO@PDA)‐incorporated composite scaffold (MD/PCL) is fabricated using 3D printing as the bottom layer. The physicochemical and mechanical properties of the bilayer scaffold meet the requirements in designing and fabricating the osteochondral scaffold, especially a strong interface possessed between the two layers. By in vitro study, the integrated scaffold stimulates proliferation, chondrogenic differentiation, and osteogenic differentiation of human bone mesenchymal stem cells. Moreover, the integrated bilayer scaffold exhibits well repair ability to facilitate simultaneous regeneration of cartilage and subchondral bone after implanting into the osteochondral defect in rats. In addition, cartilage “tidemarks” completely regenerated after 12 weeks of implantation of the bilayer scaffold, which indicates no tissue disjunctions formed between the regenerated cartilage and subchondral bone.

Establishment of a rabbit liver metastasis model by percutaneous puncture of the spleen and implantation of the VX2 tumor strain under CT guidance

This study aimed to compare the feasibility, success rate, and safety of establishing a rabbit VX2 liver metastasis model by percutaneous splenic implantation under CT guidance and open splenic implantation of the VX2 tumor strain. Fifty-two New Zealand white rabbits were randomly divided into group A (the percutaneous puncture group) (n = 26) and group B (the laparotomy group) (n = 26). In group A, 26 New Zealand white rabbits were implanted with tumor strains by percutaneous splenic puncture under CT guidance. In group B, 26 New Zealand white rabbits were implanted with tumor strains in the spleen by laparotomy. After 2–3 weeks of implantation, both group A and group B underwent MRI to confirm tumor growth in the spleen and metastasis to the liver. Two experimental rabbits randomly selected from groups A and B were killed for pathological examination. The success rate, complication rate, and operation time in groups A and B were compared and analyzed. A total of 23 rabbits in group A were successfully induced, and the success rate was 88.5% (23/26). The average time of operation was 14.42 ± 3.26 min. A total of 22 rabbits in group B were successfully induced, and the success rate was 84.6% (22/26). The average time of operation in group B was 23.69 ± 5.27 min. There was no significant difference in the success rate of induction between the two groups (P > 0.05). The MRI manifestations of liver metastases were multiple nodular and punctate abnormal signal shadows in the liver. Hematoxylin–eosin (HE) staining showed a large number of tumor cells in the tumor area. CT-guided percutaneous splenic implantation of the VX2 tumor strain to establish a rabbit liver metastasis model is a minimally invasive and feasible inducing method. The success rate of this technique is not lower than that of open splenic implantation, with low incidence of complications, and short operation time.

In vitro/in vivo identification of zein degraded peptides using HPLC-MS/MS and their safety evaluation

The identification of degraded products of implanted scaffolds is desirable to avoid regulatory concerns. In vivo identification of products produced by the degradation of natural protein-based scaffolds is complex and demands the establishment of a routine analytical method. In this study, we developed a method for the identification of peptides produced by the degradation of zein both in vitro and in vivo using high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). For in vitro experiments, zein was degraded enzymatically and analyzed produced peptides. In vitro study showed cytocompatibility of peptides present in the hydrolysate of zein with no induction of apoptosis and cell senescence. For in vivo experiment, zein gels were prepared and subcutaneously implanted in rats. Peptides produced by the degradation of zein were identified and few were selected as targeted (unique peptides) and two peptides were synthesized as the reference sequence of these peptides. Further, peptide analysis using HPLC-MS/MS of different organs was performed after 2 and 8 weeks of implantation of zein gel in rats. It was found that zein-originated peptides were accumulated in different organs. QQHIIGGALF or peptides with same fractions were identified as unique peptides. These peptides were also found in control rats with regular rat feed, which means the degradation of implanted zein biomaterial produced food related peptides of non-toxic nature. Furthermore, hemotoxylin and eosin (H&E) staining exhibited normal features. Overall, zein degraded products showed cytocompatibility and did not induce organ toxicity, and QQHIIGGALF can act as a standard peptide for tracing and determining zein degradation. The study also provides the feasibility of complex analysis on identification and quantification of degradation products of protein-based scaffolds.