Smart Nanosacrificial Layer on the Bone Surface Prevents Osteoporosis through Acid-Base Neutralization Regulated Biocascade Effects.

Osteoporosis is a global chronic disease characterized by severe bone loss and high susceptibility to fragile fracture. It is widely accepted that the origin acidified microenvironment created by excessive osteoclasts causes irreversible bone mineral dissolution and organic degradation during osteoclastic resorption. However, current clinically available approaches are mainly developed from the perspective of osteoclast biology rather than the critical acidified niche. Here, we developed a smart "nanosacrificial layer" consisting of sodium bicarbonate (NaHCO3)-containing and tetracycline-functionalized nanoliposomes (NaHCO3-TNLs) that can target bone surfaces and respond to external secreted acidification from osteoclasts, preventing osteoporosis. In vitro and in vivo results prove that this nanosacrificial layer precisely inhibits the initial acidification of osteoclasts and initiates a chemically regulated biocascade to remodel the bone microenvironment and realize bone protection: extracellular acid-base neutralization first inhibits osteoclast function and also promotes its apoptosis, in which the apoptosis-derived extracellular vesicles containing RANK (receptor activator of nuclear factor-κ B) further consume RANKL (RANK ligand) in serum, achieving comprehensive osteoclast inhibition. Our therapeutic strategy for osteoporosis is based on original and precise acid-base neutralization, aiming to reestablish bone homeostasis by using a smart nanosacrificial layer that is able to induce chemically regulated biocascade effects. This study also provides a novel understanding of osteoporosis therapy in biomedicine and clinical treatments.

Current advances in the development of natural meniscus scaffolds: innovative approaches to decellularization and recellularization.

The increasing rate of injuries to the meniscus indicates the urgent need to develop effective repair strategies. Irreparably damaged menisci can be replaced and meniscus allografts represent the treatment of choice; however, they have several limitations, including availability and compatibility. Another approach is the use of artificial implants but their chondroprotective activities are still not proved clinically. In this situation, tissue engineering offers alternative natural decellularized extracellular matrix (ECM) scaffolds, which have shown biomechanical properties comparable to those of native menisci and are characterized by low immunogenicity and promising regenerative potential. In this article, we present an overview of meniscus decellularization methods and discuss their relative merits. In addition, we comparatively evaluate cell types used to repopulate decellularized scaffolds and analyze the biocompatibility of the existing experimental models. At present, acellular ECM hydrogels, as well as slices and powders, have been explored, which seems to be promising for partial meniscus regeneration. However, their inferior biomechanical properties (compressive and tensile stiffness) compared to natural menisci should be improved. Although an optimal decellularized meniscus scaffold still needs to be developed and thoroughly validated for its regenerative potential in vivo, we believe that decellularized ECM scaffolds are the future biomaterials for successful structural and functional replacement of menisci.

Targeting initial tumour-osteoclast spatiotemporal interaction to prevent bone metastasis.

Bone is the most common site of metastasis, and although low proliferation and immunoediting at the early stage make existing treatment modalities less effective, the microenvironment-inducing behaviour could be a target for early intervention. Here we report on a spatiotemporal coupling interaction between tumour cells and osteoclasts, and named the tumour-associated osteoclast 'tumasteoclast'-a subtype of osteoclasts in bone metastases induced by tumour-migrasome-mediated cytoplasmic transfer. We subsequently propose an in situ decoupling-killing strategy in which tetracycline-modified nanoliposomes encapsulating sodium bicarbonate and sodium hydrogen phosphate are designed to specifically release high concentrations of hydrogen phosphate ions triggered by tumasteoclasts, which depletes calcium ions and forms calcium-phosphorus crystals. This can inhibit the formation of migrasomes for decoupling and disrupt cell membrane for killing, thereby achieving early prevention of bone metastasis. This study provides a research model for exploring tumour cell behaviour in detail and a proof-of-concept for behaviour-targeting strategy.

Percutaneous vertebroplasty versus balloon kyphoplasty for treatment of osteoporotic vertebral compression fracture: a meta-analysis of randomised and non-randomised controlled trials.

PURPOSE: There is still debate over whether vertebroplasty (VP) or kyphoplasty (KP) is superior for the treatment of osteoporosis vertebral compression fractures (VCFs). We performed a systematic review and meta-analysis of randomised and non-randomised controlled trials comparing VP with KP to reach a relatively conclusive answer. METHODS: We searched computerised databases comparing efficacy and safety of VP and KP in osteoporotic fractures. These trials reported pain relief (Visual Analogue Scale), disability (Oswestry disability score) and complications (i.e., cement leakage, incident fractures) as the primary outcome. RESULTS: Eight studies involving 848 patients were identified. The outcome showed that VP is more effective in the short-term (no more than seven days) pain relief. Kyphoplasty had a superior capability for intermediate-term (around three months) functional improvement. As for long-term pain relief and functional improvement, there is no significant difference between these two interventions. Consistently, both interventions have similar risk for subsequent fracture and cement leakage. CONCLUSION: Thus considering the higher cost of the KP procedure, we recommend VP over KP for the treatment of osteoporotic VCFs.

Correlation Analysis Between Basic Diseases and Subsequent Vertebral Fractures After Percutaneous Kyphoplasty (PKP) for Osteoporotic Vertebral Compression Fractures.

BACKGROUND: Percutaneous kyphoplasty (PKP) is a widely accepted surgical treatment modality for painful osteoporotic vertebral compression fractures. The risk factors cause of subsequent vertebral fractures after PKP are debated. OBJECTIVES: To evaluate risk factors for the occurrence of new vertebral compression fractures after PKP. STUDY DESIGN: A retrospective study. SETTING: A single-center inpatient population. METHODS: A total of 921 patients (1,152 vertebrae) with PKP were investigated. Among those patients, 111 patients (155 levels) incurred refractures after PKP. RESULTS: The average bone mineral density was -3.27 in the "refracture"group and -3.00 in the "no fracture" group (P = 0.031). Morbidities of women were significantly higher in the "refracture" group (90.99%) compared with the "no fracture" group (81.73%) (P = 0.015). Among the basic diseases, several diseases (history of previously fracture, previously osteoporosis, gallstone disease, stomach disease, and ovariectomy) are associated with refractures after PKP (P < 0.05). And antiosteoporotic treatment (calcium + vitamin D or zoledronate) after PKP can also significantly reduce the occurrence of refracture (P < 0.000). In addition, logistic regression analysis also showed that most of the above contents had significant correlation with the refracture after PKP (P < 0.05), except for gallstone disease (P = 0.362). LIMITATIONS: Retrospective study, single center. CONCLUSION: Osteoporosis is the main cause of refracture after PKP. Elderly women were found to be more susceptible than elderly men to refracture. Patients with a history of previously fracture, previously osteoporosis, stomach ulcer, and ovariectomy are more likely to be refracture. Antiosteoporosis treatment (calcium + vitamin D or zoledronate) after PKP can reduce the risk of refracture.

Desktop-stereolithography 3D printing of a radially oriented extracellular matrix/mesenchymal stem cell exosome bioink for osteochondral defect regeneration.

Mitochondrial dysfunction and oxidative stress damage are hallmarks of osteoarthritis (OA). Mesenchymal stem cell (MSC)-derived exosomes are important in intercellular mitochondria communication. However, the use of MSC exosomes for regulating mitochondrial function in OA has not been reported. This study aimed to explore the therapeutic effect of MSC exosomes in a three dimensional (3D) printed scaffold for early OA therapeutics. Methods: We first examined the mitochondria-related proteins in normal and OA human cartilage samples and investigated whether MSC exosomes could enhance mitochondrial biogenesis in vitro. We subsequently designed a bio-scaffold for MSC exosomes delivery and fabricated a 3D printed cartilage extracellular matrix (ECM)/gelatin methacrylate (GelMA)/exosome scaffold with radially oriented channels using desktop-stereolithography technology. Finally, the osteochondral defect repair capacity of the 3D printed scaffold was assessed using a rabbit model. Results: The ECM/GelMA/exosome scaffold effectively restored chondrocyte mitochondrial dysfunction, enhanced chondrocyte migration, and polarized the synovial macrophage response toward an M2 phenotype. The 3D printed scaffold significantly facilitated the cartilage regeneration in the animal model. Conclusion: This study demonstrated that the 3D printed, radially oriented ECM/GelMA/exosome scaffold could be a promising strategy for early OA treatment.

Interpenetrating polymer network scaffold of sodium hyaluronate and sodium alginate combined with berberine for osteochondral defect regeneration.

Degradation of the articular cartilage and structural remodeling of the subchondral bone are regarded as the two major pathological characteristics of osteoarthritis. This study aimed to investigate the effect of an interpenetrating polymer network (IPN) of a sodium hyaluronate and sodium alginate (HA/SA) scaffold combined with berberine (BER) on osteochondral repair. We first developed an IPN scaffold of HA/SA and evaluated its characteristics. Then, we analyzed the effect of the HA/SA scaffold combined with BER on the healing of osteochondral defects in vivo. Finally, we explored the mechanism of this system in osteochondral repair. The results showed that the system could simultaneously regenerate not only the cartilage but also the subchondral bone. Our results also revealed that the subchondral bone was partially repaired by activating the Wnt signaling pathway and the cartilage was protected from degeneration by the upregulation of autophagy. This study demonstrated that the combination of the IPN scaffold of HA/SA and BER is a promising strategy for the osteochondral defect regeneration.

Mechanism of formation of intravertebral clefts in osteoporotic vertebral compression fractures: An in vitro biomechanical study.

BACKGROUND CONTEXT: Intravertebral clefts (IVCs) are vacuum-like cavities commonly associated with osteoporotic vertebral compression fractures (OVCFs). IVCs promote cement leakage during kyphoplasty, suggesting a physical link with the basivertebral foramen, although this is uncertain. PURPOSE: The present study aims to create IVCs in mechanical experiments on cadaveric spines in order to clarify their pathogenesis, structure, and links with the basivertebral foramen. STUDY DESIGN AND METHODS: In total, 15 three-vertebra lumbar specimens from five cadavers aged 68 to 71 years were subjected to axial compressive overload followed by cyclic loading in flexion and extension to create an OVCF together with an IVC. Computed tomography scans and radiographs were used to confirm structural changes and micro-CT was used to measure trabecular bone properties in five specimens. Unipedicular vertebroplasty was then performed on 10 damaged specimens until fluoroscopy revealed extravasation of cement. RESULTS: In every specimen, loading created an OVCF with an IVC. Dissection and imaging showed that the IVC was always connected with the basivertebral foramen. The central vertebral region, including the IVC, had the lowest connectivity density, trabecular number, and bone volume fraction, and the highest trabecular separation. Vertebroplasty caused cement leakage through the basivertebral foramen in nine specimens and into an adjacent disc in one specimen. CONCLUSION: Cyclic loading in flexion and extension applied to a fractured osteoporotic vertebra can create an IVC, which then allows cement leakage via the basivertebral foramen.

Periosteum Extracellular-Matrix-Mediated Acellular Mineralization during Bone Formation.

Cell-mediated mineralization is essential for bone formation and regeneration. In this study, it is proven that extracellular matrix (ECM) of decellularized periosteum can play an initiative and independent role in bone-like apatite formation. Using decellularized periosteum scaffold, it is revealed that ECM scaffold itself can promote critical bone defect regeneration and nude mouse ectopic ossification. The natural collagen matrix of decellularized periosteum can serve as a 3D structural template for Ca-P nuclei initiation, controlling the size and orientation of bone-like mineral crystals. The naturally cross-linked and highly ordered 3D fibrillar network of decellularized periosteum not only provides a model for mimicking mineralization in vitro and in vivo to elucidate the important functions of ECM in bone formation and regeneration, but also can be a promising biomaterial for bone tissue engineering and clinical application.

Cement Distribution Patterns Are Associated with Recompression in Cemented Vertebrae After Percutaneous Vertebroplasty: A Retrospective Study.

OBJECTIVE: To reevaluate the cement distribution patterns and further investigate associations between cement distribution patterns and the occurrence rates of recompression in cemented vertebrae after percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fractures. METHODS: Two hundred twenty-four patients with a mean age of 71.9 years were enrolled and treated with single-level PVP between June 2012 and July 2015. The mean follow-up time was 16.5 months. Data from medical records and radiographs were collected and analyzed. Cement distribution patterns were divided into 4 cement distribution patterns extending from the traditional 2 patterns: interlocked solid pattern (LS) and uninterlocked solid pattern (ULS); contiguous trabecular pattern (CT) and discontiguous trabecular pattern (DCT). Differences in treatment efficacy and the occurrence rates of recompression in cemented vertebrae were compared for both groups using the Wilcoxon rank sum test and chi-squared test. RESULTS: Thirty-seven patients who underwent PVP developed recompression in cemented vertebrae. Recompression in cemented vertebrae was significantly more frequent in the ULS and DCT groups than in the LS and CT groups (P < 0.05 or 0.001), with the Visual Analogue Scale score at the time of final follow-up was also significantly higher in the ULS and DCT groups (P < 0.001). CONCLUSIONS: Significant associations were found between cement distribution patterns and recompression in cemented vertebrae, which affected the clinical outcome in patients after PVP. A higher incidence of recompression in cemented vertebrae was seen in patients with treated vertebrae exhibiting ULS pattern or DCT pattern.

The amelioration of cartilage degeneration by photo-crosslinked GelHA hydrogel and crizotinib encapsulated chitosan microspheres.

The present study aimed to investigate the synergistic therapeutic effect of decreaseing cartilage angiogenesis via exposure to crizotinib encapsulated by chitosan microspheres and photo-crosslinked hydrogel, with the goal of evaluating crizotinib as a treatment for osteoarthritis. First, we developed and evaluated the characteristics of hydrogels and chitosan microspheres. Next, we measured the effect of crizotinib on the cartilage degeneration induced by interleukin-1ß in chondrocytes. Crizotinib ameliorated the pathological changes induced by interleukin-1ß via its anti-angiogenesis function. In addition, we surgically induced osteoarthritis in mice, which were then injected intra-articularly with crizotinib-loaded biomaterials. Cartilage matrix degradation, expression of vascular endothelial growth factor and extracellular signal-regulated kinases 1/2 were evaluated after surgery. Treatment with the combination of crizotinib-loaded biomaterials retarded the progression of surgically induced osteoarthritis. Crizotinib ameliorated cartilage matrix degradation by promoting anti-angiogenesis and impeding extracellular signal-regulated kinases 1/2 signaling pathway. Our results demonstrate that the combination of photo-crosslinked hydrogel and crizotinib-loaded chitosan microspheres might represent a promising strategy for osteoarthritis treatment.

Effects of annulus defects and implantation of poly(lactic-co-glycolic acid) (PLGA)/fibrin gel scaffolds on nerves ingrowth in a rabbit model of annular injury disc degeneration.

BACKGROUND: Growth of nerve fibers has been shown to occur in a rabbit model of intravertebral disc degeneration (IVD) induced by needle puncture. As nerve growth may underlie the process of chronic pain in humans affected by disc degeneration, we sought to investigate the factors underlying nerve ingrowth in a minimally invasive annulotomy rabbit model of IVD by comparing the effects of empty disc defects with those of defects filled with poly(lactic-co-glycolic acid)/fibrin gel (PLGA) plugs. METHODS: New Zealand white rabbits (n = 24) received annular injuries at three lumbar levels (L3/4, L4/5, and L5/6). The discs were randomly assigned to four groups: (a) annular defect (1.8-mm diameter; 4-mm depth) by mini-trephine, (b) annular defect implanted with a PLGA scaffold containing a fibrin gel, (c) annular puncture by a 16G needle (5-mm depth), and (d) uninjured L2/3 disc (control). Disc degeneration was evaluated by radiography, MRI, histology, real-time PCR, and analysis of proteoglycan (PG) content. Nerve ingrowth into the discs was assessed by immunostaining with the nerve marker protein gene product 9.5. RESULTS: Injured discs showed a progressive disc space narrowing with significant disc degeneration and proteoglycan loss, as confirmed by imaging results, molecular and compositional analysis, and histological examinations. In 16G punctured discs, nerve ingrowth was observed on the surface of scar tissue. In annular defects, nerve fibers were found to be distributed along small fissures within the fibrocartilaginous-like tissue that filled the AF. In discs filled with PLGA/ fibrin gel, more nerve fibers were observed growing deeper into the inner AF along the open annular track.  In addition, innervations scores showed significantly higher than those of punctured discs and empty defects. A limited vascular proliferation was found in the injured sites and regenerated tissues. CONCLUSIONS: Nerve ingrowth was significantly higher in PLGA/fibrin-filled discs than in empty defects. Possible explanations include (i) annular fissures along the defect and early loss of proteoglycan may facilitate the ingrowth process and (ii) biodegradable PLGA/fibrin gel may promote adverse growth of nerves and blood vessels into deeper parts of injured disc. The rabbit annular defect model of disc degeneration appears suitable to investigate the effects of nerve ingrowth in relation to pain generation.

An injectable nucleus pulposus cell-modified decellularized scaffold: biocompatible material for prevention of disc degeneration.

We developed a nucleus pulposus cell (NPC)-modulated decellularized small intestinal submucosa (SIS) scaffold, and assessed the ability of this material to prevent Intervertebral disc degeneration (IVD) degeneration. Decellularized porcine SIS was squashed into particles and the biological safety and efficiency of these particles were evaluated. Next, SIS particles were seeded with rabbit NPCs, cultured for two months in vitro, decellularized again and suspended for intervertebral injection. We demonstrated that use of the decellularization protocol resulted in the removal of cellular components with maximal retention of extracellular matrix. The xenogeneic decellularized SIS did not display cytotoxicity in vitro and its application prevented NPC degradation. Furthermore, the xenogeneic SIS microparticles were effective in preventing IVD progression in vivo in a rabbit disc degeneration model. In conclusion, our study describes an optimized method for decellularized SIS preparation and demonstrated that the material is safe and effective for treating IVD degeneration.

Photo-crosslinked HAMA hydrogel with cordycepin encapsulated chitosan microspheres for osteoarthritis treatment.

Autophagy is a protective mechanism in normal cartilage. The present study aimed to investigate the synergistic therapeutic effect of promotion of chondrocyte autophagy via exposure to cordycepin encapsulated by chitosan microspheres (CM-cordycepin) and photo-crosslinked hyaluronic acid methacrylate (HAMA) hydrogel, with the goal of evaluating CM-cordycepin as a treatment for patients with osteoarthritis. First, we developed and evaluated the characteristics of HAMA hydrogels and chitosan microspheres. Next, we measured the effect of cordycepin on cartilage matrix degradation induced by IL1-ß in chondrocytes and an ex vivo model. Cordycepin protects cartilage from degradation partly by activation of autophagy. Moreover, we surgically induced osteoarthritis in mice, which were injected intra-articularly with CM-cordycepin and HAMA. The combination of CM-cordycepin and HAMA hydrogel retarded the progression of surgically induced OA. Cordycepin ameliorated cartilage matrix degradation at least partially by inducing autophagy in vivo. Our results demonstrate that the combination of cordycepin encapsulated by CMs and photo-crosslinked HAMA hydrogel could be a promising strategy for treating patients with osteoarthritis.

Biodegradable and biocompatible high elastic chitosan scaffold is cell-friendly both in vitro and in vivo.

Biodegradable and biocompatible macromolecule chitosan has been favored for a variety of clinical applications. We reported herein the fabrication of a novel chitosan scaffold with high elasticity. This scaffold can be easily compressed and thus enable the insertion of such scaffold into surgical lesions during minimal invasive surgeries. In addition, this novel scaffold can restore its shape when released. We evidenced that this high elastic scaffold has better biocompatibility than traditional chitosan scaffold. Therefore, this new chitosan material might lead to the manufacture of a variety of novel biodegradable biomedical materials and devices.

Trabecular Microstructure and Damage Affect Cement Leakage From the Basivertebral Foramen During Vertebral Augmentation.

STUDY DESIGN: A prospective study on cadaver specimens. OBJECTIVE: To explore why cement leakage from basivertebral foramen (BF) easily occurs during vertebral augmentation procedures. SUMMARY OF BACKGROUND DATA: Type B (through BF, basivertebral foramen) cement leakage is the most common type after vertebral augmentation, but the mechanism of this is still controversial. The contribution of vertebral trabecular bone orientation and trabecular damage during compression fracture to cement leakage is still unknown. METHODS: In this study, 12 fresh-frozen human lumbar spines (T12-L5) were collected and divided into 24 three-segment units. Mechanical testing was performed to simulate a compression fracture. MicroCT were performed on all segments before and after mechanical testing, and trabecular microstructure of the superior, middle (containing BF), and inferior 1/3 of each vertebral body was analyzed. The diameter variation of intertrabecular space before and after compression fracture was used to quantify trabecular injury. After mechanical testing, vertebral augmentation, and imaging-based diagnosis were used to evaluate cement leakage. RESULTS: Trabecular bone microstructural parameters in middle region (containing BF) were lower than those of the superior or inferior regions (P < 0.01). After compressive failure, 3D-reconstruction of the vertebral body by MicroCT demonstrated that intertrabecular distance in the middle region was markedly increased. Type B cement leakage was the most common type after vertebral augmentation, as found previously in Wang et al. (Spine J 2014;14: 1551-1558). CONCLUSION: The presence of the BF and the relative sparsity of trabecular bone make the middle region of the vertebral body the mechanically weakest region. Trabecular bone in middle region suffered the most severe damage during compressive failure of the vertebral body, which resulted in the greatest intervertebral spacing, and subsequently the highest percentage of type B cement leakage. These data suggest specific mechanisms by which cement may leak from the BF, and the contribution of trabecular microstructure and trabecular injury. LEVEL OF EVIDENCE: 4.

Minimal invasive annulotomy for induction of disc degeneration and implantation of poly (lactic-co-glycolic acid) (PLGA) plugs for annular repair in a rabbit model.

BACKGROUND: The rabbit disc model is useful for the study of intervertebral disc (IVD) degeneration and experimental therapeutic interventions. The annulotomy-induced disc models present several drawbacks, particularly an excessive disruption of disc integrity and a rapidly disc degeneration; therefore, this study sought to establish a minimal invasive annulotomy for induction of disc degeneration model, combined to annulus repair using implantation of a PLGA (poly lactic-co-glycolic acid) plug. METHODS: New Zealand white rabbits (n = 24) received annular injuries in three discs (L3/4, L4/5 and L5/6). The experimental discs were randomly assigned to four groups: (a) annular defect with a 1.8 mm diameter mini-trephine; (b) annular puncture by 16G needle; (c) annular defect with a PLGA plug implanted by press-fit fashion; (d) uninjured L2/3 disc served as control. Postsurgical x-ray, MRI examination, and real-time PCR analysis were performed at 1, 3 and 6 months. Gross morphology and histology were evaluated at postoperative 6 months. RESULTS: Radiographic examinations showed a slow, progressive disc space narrowing and a significant degree of disc degeneration on MRI grade in the injured discs at 6 months in all rabbits. Histological examinations and aggrecan, Col1A1, Col2A1 and matrix metalloprotease (MMP)-3 mRNA expression confirmed the disc degeneration, supporting the imaging results. The PLGA implantation reduced the marked loss of T2-weighted signal intensity seen at MRI in the injured discs and slowly decreased the disc height index (DHI) over the follow-up period. HE/Safranin O staining showed that annular defect was replaced by regenerated connective tissue with significant loss of proteoglycan content. CONCLUSIONS: The minimally invasive approach for the creation of annular defects by an appropriately sized mini-Trephine is a suitable option for the study of disc degeneration in a rabbit model. Implantation of a suitable PLGA plug induced a successful repair of the annulus fibrosus within the degenerated disc, and retarded the degenerative process in the annular injury model.

Atlantoaxial Joint Interlocking Following Type II Odontoid Fracture Associated with Posterolateral Atlantoaxial Dislocation: a Case Report and Review of Published Reports.

A rare case of atlantoaxial lateral mass joint interlocking secondary to traumatic posterolateral C1,2 complete dislocation associated with type II odontoid fracture is herein reported and the impact of atlantoaxial joint interlocking on fracture reduction discussed. A 72-year-old man presented with traumatic atlantoaxial lateral mass joint interlocking without spinal cord signal change, the diagnosis being confirmed by radiography and 3-D reconstruction digital anatomy. Posterior internal fixation was performed after failure to achieve closed reduction by skull traction. After many surgical attempts at setting had failed because of interlocking of the lateral mass joints, reduction was achieved by compressing the posterior parts of the atlantal and axial screws. Odontoid bone union and C1,2 posterior bone graft fusion were eventually obtained by the 12-month follow-up. The patient had a complete neurological recovery with no residual neck pain or radiculopathy.

Intra-articular delivery of sinomenium encapsulated by chitosan microspheres and photo-crosslinked GelMA hydrogel ameliorates osteoarthritis by effectively regulating autophagy.

Reduced expression of autophagy regulators has been observed in pathological cartilage in humans and mice. The present study aimed to investigate the synergistic therapeutic effect of promotion of chondrocyte autophagy via exposure to sinomenium (SIN) encapsulated by chitosan microspheres (CM-SIN) and photo-crosslinked gelatin methacrylate (GelMA) hydrogel, with the goal of evaluating CM-SIN as a treatment for patients with osteoarthritis. First, we fabricated and characterized GelMA hydrogels and chitosan microspheres. Next, we measured the effect of SIN on cartilage matrix degradation induced by IL1-ß in chondrocytes and an ex vivo model. SIN ameliorated the pathological changes induced by IL1-ß at least partially through activation of autophagy. Moreover, we surgically induced osteoarthritis in mice, which were injected intra-articularly with CM-SIN and GelMA. Cartilage matrix degradation and chondrocyte autophagy were evaluated 4 and 8 weeks after surgery. Treatment with the combination of CM-SIN and GelMA retarded the progression of surgically induced OA. SIN ameliorated cartilage matrix degradation at least partially by inducing autophagy in vivo. Our results demonstrate that injection of the combination of GelMA hydrogel and CM-SIN could be a promising strategy for treating patients with osteoarthritis.

Decellularized allogeneic intervertebral disc: natural biomaterials for regenerating disc degeneration.

Intervertebral disc degeneration is associated with back pain and disc herniation. This study established a modified protocol for intervertebral disc (IVD) decellularization and prepared its extracellular matrix (ECM). By culturing mesenchymal stem cells (MSCs)(3, 7, 14 and 21 days) and human degenerative IVD cells (7 days) in the ECM, implanting it subcutaneously in rabbit and injecting ECM microparticles into degenerative disc, the biological safety and efficacy of decellularized IVD was evaluated both in vitro and in vivo. Here, we demonstrated that cellular components can be removed completely after decellularization and maximally retain the structure and biomechanics of native IVD. We revealed that allogeneic ECM did not evoke any apparent inflammatory reaction in vivo and no cytotoxicity was found in vitro. Moreover, IVD ECM can induce differentiation of MSCs into IVD-like cells in vitro. Furthermore, allogeneic ECM microparticles are effective on the treatment of rabbit disc degeneration in vivo. In conclusion, our study developed an optimized method for IVD decellularization and we proved decellularized IVD is safe and effective for the treatment of degenerated disc diseases.