Human Infrapatellar Fat Pad Mesenchymal Stem Cell-derived Extracellular Vesicles Purified by Anion Exchange Chromatography Suppress Osteoarthritis Progression in a Mouse Model.

BACKGROUND: Extracellular vesicles derived from mesenchymal stem cells (MSCs) show great promise in treating osteoarthritis (OA). However, studies from the perspective of clinical feasibility that consider an accessible cell source and a scalable preparation method for MSC-extracellular vesicles are lacking. QUESTIONS/PURPOSES: (1) Does an infrapatellar fat pad obtained from patients undergoing TKA provide a suitable source to provide MSC-extracellular vesicles purified by anion exchange chromatography? Using an in vivo mouse model for OA in the knee, (2) how does injection of the infrapatellar fat pad-derived MSC-extracellular vesicles alter gait, cartilage structure and composition, protein expression (Type II collagen, MMP13, and ADAMTS5), subchondral bone remodeling and osteophytes, and synovial inflammation? METHODS: The infrapatellar fat pad was collected from three patients (all female; 62, 74, 77 years) during TKA for infrapatellar fat pad-derived MSC culturing. Patients with infection, rheumatic arthritis, and age > 80 years were excluded. MSC-extracellular vesicles were purified by anion exchange chromatography. For the animal study, we used 30 male C57BL/6 mice aged 10 weeks, divided into six groups. MSC-extracellular vesicles were injected weekly into the joint of an OA mouse model during ACL transection (ACLT). To answer our first research question, we characterized MSCs based on their proliferative potential, differentiation capacity, and surface antigen expression, and we characterized MSC-extracellular vesicles by size, morphology, protein marker expression, and miRNA profile. To answer our second research question, we evaluated the effects of MSC-extracellular vesicles in the OA mouse model with quantitative gait analysis (mean pressure, footprint area, stride length, and propulsion time), histology (Osteoarthritis Research Society International Score based on histologic analysis [0 = normal to 24 = very severe degeneration]), immunohistochemistry staining of joint sections (protein expression of Type II collagen, MMP13, and ADAMTS5), and micro-CT of subchondral bone (BV/TV and Tb.Pf) and osteophyte formation. We also examined the mechanism of action of MSC-extracellular vesicles by immunofluorescent staining of the synovium membrane (number of M1 and M2 macrophage cells) and by analyzing their influence on the expression of inflammatory factors (relative mRNA level and protein expression of IL-1ß, IL-6, and TNF-α) in lipopolysaccharide-induced macrophages. RESULTS: Infrapatellar fat pads obtained from patients undergoing TKA provide a suitable cell source for producing MSC-extracellular vesicles, and anion exchange chromatography is applicable for isolating MSC-extracellular vesicles. Cultured MSCs were spindle-shaped, proliferative at Passage 4 (doubling time of 42.75 ± 1.35 hours), had trilineage differentiation capacity, positively expressed stem cell surface markers (CD44, CD73, CD90, and CD105), and negatively expressed hematopoietic markers (CD34 and CD45). MSC-extracellular vesicles purified by anion exchange chromatography had diameters between 30 and 200 nm and a typical cup shape, positively expressed exosomal marker proteins (CD63, CD81, CD9, Alix, and TSG101), and carried plentiful miRNA. Compared with the ACLT group, the ACLT + extracellular vesicle group showed alleviation of pain 8 weeks after the injection, indicated by increased area (0.67 ± 0.15 cm2 versus 0.20 ± 0.03 cm2, -0.05 [95% confidence interval -0.09 to -0.01]; p = 0.01) and stride length (5.08 ± 0.53 cm versus 6.20 ± 0.33 cm, -1.12 [95% CI -1.86 to -0.37]; p = 0.005) and decreased propulsion time (0.22 ± 0.06 s versus 0.11 ± 0.04 s, 0.11 [95% CI 0.03 to 0.19]; p = 0.007) in the affected hindlimb. Compared with the ACLT group, the ACLT + extracellular vesicles group had lower Osteoarthritis Research Society International scores after 4 weeks (8.80 ± 2.28 versus 4.80 ± 2.28, 4.00 [95% CI 0.68 to 7.32]; p = 0.02) and 8 weeks (16.00 ± 3.16 versus 9.60 ± 2.51, 6.40 [95% CI 2.14 to 10.66]; p = 0.005). In the ACLT + extracellular vesicles group, there was more-severe OA at 8 weeks than at 4 weeks (9.60 ± 2.51 versus 4.80 ± 2.28, 4.80 [95% CI 0.82 to 8.78]; p = 0.02), indicating MSC-extracellular vesicles could only delay but not fully suppress OA progression. Compared with the ACLT group, the injection of MSC-extracellular vesicles increased Type II collagen expression, decreased MMP13 expression, and decreased ADAMTS5 expression at 4 and 8 weeks. Compared with the ACLT group, MSC-extracellular vesicle injection alleviated osteophyte formation at 8 weeks and inhibited bone loss at 4 weeks. MSC-extracellular vesicle injection suppressed inflammation; the ACLT + extracellular vesicles group had fewer M1 type macrophages than the ACLT group. Compared with lipopolysaccharide-treated cells, MSC-extracellular vesicles reduced mRNA expression and inhibited IL-1ß, IL-6, and TNF-α in cells. CONCLUSION: Using an OA mouse model, we found that infrapatellar fat pad-derived MSC-extracellular vesicles could delay OA progression via alleviating pain and suppressing cartilage degeneration, osteophyte formation, and synovial inflammation. The autologous origin of extracellular vesicles and scalable purification method make our strategy potentially viable for clinical translation. CLINICAL RELEVANCE: Infrapatellar fat pad-derived MSC-extracellular vesicles isolated by anion exchange chromatography can suppress OA progression in a mouse model. Further studies with large-animal models, larger animal groups, and subsequent clinical trials are necessary to confirm the feasibility of this technique for clinical OA treatment.

Minimally Invasive Treatment of Pelvic Fractures with Titanium Elastic Nailing: An Innovative Technology.

BACKGROUND: Minimally invasive treatment has become the most popular and effective treatment for pelvic fractures. This study aimed to evaluate the safety and efficacy of a new technique, titanium elastic nailing (TEN), for the minimally invasive treatment of pelvic fractures. METHOD: Twenty-four patients with pelvic fractures were referred to us between January 2020 to January 2022, including sixteen males and 8 females. Pelvic fractures were temporarily fixed by pelvic fixation belt accompanied by traction from the lower limb bone. Anterior pelvic ring injuries (superior ramus of pubis) and ilium fractures were treated with closed reduction and intramedullary fixation with minimally invasive TEN. Intraoperative C-arm, including pelvic anteroposterior, pelvic outlet, inlet and ilium oblique views, and O-arm fluoroscopy (intraoperative CT) were employed to assess fractures reduction and determine the location of the elastic titanium nail within the bone channel. RESULTS: By adopting closed reduction and minimally invasive incision techniques, pelvic fractures could be safely fixed by placing an elastic titanium nail in the osseous medullary cavity channels of the pelvis. Postoperative investigation indicated that the wounds of all patients were healed in the first stage without any occurrence of complications, such as injuries to the nerves, blood vessels, and important tissue structures. Patients are essential quickly after the operation and could perform the functional exercise in the early stages of the recovery. CONCLUSION: TEN can be used for minimally invasive treatment of pelvic fractures. This novel technique has no obvious complications and is worthwhile in clinical practice.

The clinical efficacy of the minimally invasive treatment of Mason type II radial head fractures using intramedullary fixation with double titanium elastic nails.

Radial head fractures (RHFs) occur most frequently among all elbow fractures. Current treatments pose several limitations for the Mason type II radial head fractures. This study was performed to evaluate the clinical efficacy of a new minimally invasive treatment for Mason type II radial head fractures using intramedullary fixation with double titanium elastic nails. Between January 2018 and December 2019, our group used double titanium elastic intramedullary nails as a minimally invasive treatment for 32 cases of Mason II type radial head fractures. After the treatments, we summarized and conducted a retrospective analysis to evaluate the surgical operation itself, the quality of the fracture reductions, the fracture healing, and any complications. The Mayo elbow function scores (MEPS) and the visual analog scale (VAS) pain scores were used to evaluate the clinical efficacy of this approach. All the patients recovered from their surgeries without any complications. We followed all the cases for an average of 12 months. The elbow extension range of motion was 5 degrees (range: 0-15 degrees), the elbow flexion range of motion was 140 degrees (range: 135-146 degrees), and the average forearm pronation range of motion was 84.1 degrees (range: 78-90 degrees). The average forearm supination range of motion was 80.4 degrees (range: 75-85 degrees). All the fractures healed (a 100% healing rate), the MEPS score was 96.7 (range: 85-100), and the MEPS ratings of excellent and good were both 100%. The VAS pain scores ranged from 0-1. The minimally invasive treatment of Mason type II radial head fractures using intramedullary fixation with double elastic nails proved to be a simple approach with a relatively short operation time. It required only a small incision with little trauma and had few complications, so it is worth consideration for wider use.

Clinical effect of using MultiLoc® nails to treat four-part proximal humeral fractures.

OBJECTIVE: This study was performed to evaluate the clinical effect of MultiLoc® nails (DePuy Synthes, Raynham, MA, USA) on the treatment of four-part proximal humeral fractures (PHFs). METHODS: From January 2014 to January 2018, 32 patients with four-part PHFs were treated with intramedullary MultiLoc® nails in our hospital. The operation time, bleeding volume, postoperative X-ray findings, and fracture healing status were recorded and analyzed. At the end of follow-up, the clinical outcome was evaluated based on the visual analog scale (VAS) score, American Shoulder and Elbow Surgeons (ASES) shoulder score, Constant-Murley score (CMS), and occurrence of any complications. RESULTS: Among all patients, the average operation time was 124.5 minutes (range, 91-152 minutes), the average amount of bleeding was 90 mL (range, 55-150 mL), and the fracture healing rate was 100%. At the end of follow-up, the mean VAS score was 1.6 ± 0.4, mean ASES score was 84.4 ± 6.3, and mean CMS was 70.3 ± 6.1; no serious complications had occurred; and the patients exhibited good recovery of shoulder function. CONCLUSIONS: MultiLoc nails® can be applied to the treatment of four-part PHFs. This surgical fixation method has no obvious complications and helps to restore shoulder function.

The treatment of complex intra-articular distal radius fractures with turning radius and distal volaris radius plate fixation.

BACKGROUND: Although distal radius fractures (DRFs) are clinically common, intra-articular DRFs accompanied by dorsally displaced free fragments are much less so. At present, it is very difficult to fix and stabilize the intra-articular distal radius fractures accompanying dorsally displaced free fragments with a plate. Our aim was to investigate the clinical effect of DRFs with distally displaced dorsal free mass treated with distal volaris radius (DVR) combined with turning of the radius via the distal palmar approach. METHODS: From 2015 to 2019, 25 patients with intra-articular distal radius fractures associated with dorsally displaced free fragments were selected and treated with distal volaris radius (DVR) combined with turning of the radius via the distal palmar approach. This study involved 14 males and 11 females, with an average age of 34.5 years (ranging from 21 to 50 years). The mean follow-up period was 16.5 months (ranging from 12 to 22 months). The dorsal displacement of the free fragments was analyzed by X-ray and three-dimensional computed tomography, allowing characterization of postoperative recovery effects by radial height, volar tilt and radial inclination. For the follow-up, we evaluated effects of the surgery by analyzing range of motion (ROM); Modified Mayo Wrist Score (MMWS); and Disabilities of Arm, Shoulder and Hand (DASH) score. Postoperative wound recovery and complications were also monitored to evaluate the clinical therapeutic effects of the surgical procedures. RESULTS: X-ray showed that all patients showed reduced fractures, well-healed wounds and recovered function with no obvious complications. Based on the follow-up, patients had a mean radial height of 10.5 mm (ranging from 8.1 to 12.6 mm), mean MMWS of 78.8° (ranging from 61° to 90°), mean DASH score of 16.25 (ranging from 11 to 21), mean ROM for volar flexion of 76.5° (ranging from 62° to 81°), mean ROM for dorsiflexion of 77.1° (ranging from 59 to 83) and mean VAS score of 1.4 (ranging from 1 to 3). CONCLUSION: Treatment of the intra-articular distal radius fractures accompanying dorsally displaced free fragments with turning of the radius and the DVR plate system via the distal palmar approach is effective and has no obvious complications.

The design of an "H" joystick for closed reduction and its application in segmental and comminuted femoral shaft fractures: an innovative technique.

BACKGROUND: Closed reduction and locked intramedullary nailing has become a common surgical method in the treatment of femoral shaft fractures. Overlap and rotation displacements can usually be corrected through the use of an orthopedic traction table. However, lateral displacement and angulation persist. METHODS: In this paper, we describe a joystick that can be used in the closed reduction of a fracture. It can correct lateral displacement and angulation, and has the advantage of multi-direction reduction. The device described in this paper includes two parallel horizontal joysticks, one vertical main joystick and four assistant rods. Moreover, there are many specific spacing holes in the two parallel horizontal joysticks and a groove structure in the vertical main joystick. When the main "H" joystick is pressed, it can adjust lateral displacements and angulation because of the lever principle. The distance between parallel horizontal joysticks and assistant rods can be adjusted to the fracture position and body mass index of different patients. RESULTS: The study participants consisted of 11 males and 5 females with a mean age of 31.0 years. All participants had good closed reduction and achieved bony union without any complications such as infection, nerve injury, non-union, malunion, and limb length discrepancy. By using an "H" joystick, closed femoral shaft fracture reduction and locked intramedullary nailing becomes simpler and faster. CONCLUSION: Based on the use of this instrument, we can easily and conveniently obtain the correct reduction situation, which leads to better surgical results. This device can be applied in the reduction of clinical femoral fractures and gradually extended to the reduction of other fractures.

Identification of differentially expressed genes by single-cell transcriptional profiling of umbilical cord and synovial fluid mesenchymal stem cells.

The purpose of this study was to measure the heterogeneity in human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) and human synovial fluid-derived mesenchymal stem cells (hSF-MSCs) by single-cell RNA-sequencing (scRNA-seq). Using Chromium™ technology, scRNA-seq was performed on hUC-MSCs and hSF-MSCs from samples that passed our quality control checks. In order to identify subgroups and activated pathways, several bioinformatics tools were used to analyse the transcriptomic profiles, including clustering, principle components analysis (PCA), t-Distributed Stochastic Neighbor Embedding (t-SNE), gene set enrichment analysis, as well as Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. scRNA-seq was performed on the two sample sets. In total, there were 104 761 163 reads for the hUC-MSCs and 6 577 715 for the hSF-MSCs, with >60% mapping rate. Based on PCA and t-SNE analyses, we identified 11 subsets within hUC-MSCs and seven subsets within hSF-MSCs. Gene set enrichment analysis determined that there were 533, 57, 32, 44, 10, 319, 731, 1037, 90, 25 and 230 differentially expressed genes (DEGs) in the 11 subsets of hUC-MSCs and 204, 577, 30, 577, 16, 57 and 35 DEGs in the seven subsets of hSF-MSCs. scRNA-seq was not only able to identify subpopulations of hUC-MSCs and hSF-MSCs within the sample sets, but also provided a digital transcript count of hUC-MSCs and hSF-MSCs within a single patient. scRNA-seq analysis may elucidate some of the biological characteristics of MSCs and allow for a better understanding of the multi-directional differentiation, immunomodulatory properties and tissue repair capabilities of MSCs.

Titanium cable isotonic annular fixation system for the treatment of distal tibiofibular syndesmosis injury.

Distal tibiofibular syndesmosis injury (DTS) occurs frequently with ankle sprains. Current treatments pose several limitations including causing soft tissue irritation, bringing damage to fixation secondary to weight-bearing, and requiring follow-up surgeries. Here, we investigated the clinical effects of a new technique, titanium cable isotonic annular fixation, for the treatment of DTS injury. From January 2015 to June 2017, 36 patients with ankle fractures and DTS injuries had their fractures repaired with the titanium cable isotonic annular fixation system. Recovery was scored by the AOFAS ankle function score system. We also assessed the differences in ankle motion between healthy and operative joints, and recorded the complications. All patients recovered from surgery without any serious complications. We followed all the cases for 18-25 months with an average follow-up of 21.26±3.23 months. 12 months after the operation, X-ray images showed that the titanium cables were fixed in the correct position without any fracture or loosening. Additionally, no degeneration or traumatic arthritis was observed in the ankle joint. There were no incision or bone mineral density changes between the titanium fix and tibiofibular bones. Nearly all patients recovered well except for three who developed inflammation and infection. However, these three patients recovered following 1 week of intravenous antibiotics and local radiofrequency physiotherapy. According to the AOFAS scoring system, all patients achieved satisfactory recovery 12 months post operation. Our titanium cable isotonic annular fixation system has both the advantages of elastic and rigid fixations. It can restore isotonic strength of the distal tibiofibular joint, and its biomechanical performance approaches normal physiological function. After the operation, patients tolerated weight-bearing exercise and recovered joint mobility. Finally, there is no need to remove the distal tibiofibular implant after 12 weeks. Overall, it is a highly effective surgical method to treat DTS injury.

Combination of kartogenin and transforming growth factor-ß3 supports synovial fluid-derived mesenchymal stem cell-based cartilage regeneration.

Synovial fluid-derived mesenchymal stem cells (SF-MSCs) represent a superior source of stem cells and have great potential for autologous transplantation for cartilage regeneration. Transforming growth factor-ß3 (TGF-ß3) has been demonstrated to stimulate the chondrogenic differentiation of MSCs. Recently, the small molecule kartogenin (KGN) was reported to enhance chondrogenic differentiation and cartilage regeneration. The effects of KGN and TGF-ß3 on the in vitro chondrogenic differentiation of rabbit SF-MSCs were studied. The monolayer and pellet cultures of rabbit SF-MSCs were stimulated in vitro using either KGN or TGF-ß3 alone or in combination for 21 days. The in vivo therapeutic effects of KGN combined with TGF-ß3 were studied using an intra-articular delivery of autologous rabbit SF-MSCs to cartilage defects in a rabbit model. Compared to a single treatment, the in vitro results demonstrated that the combination of KGN and TGF-ß3 resulted in significantly increased protein expression levels of type II collagen (COL II) and SRY-box 9 (SOX9) and decreased the expression level of type X collagen (COL X). Compared with the regenerated cartilage in the single treatment groups, the intra-articular injection of rabbit SF-MSCs mixed with TGF-ß3 and KGN exhibited substantial amounts of regenerated cartilage in the defective areas in the medial femoral condyles. We noted that the thicker, hyaline-like cartilaginous tissue contained abundant levels of extracellular matrix, which is characteristic of cartilage. This study demonstrated that TGF-ß3 and KGN exhibit synergistic effects for the promotion of the chondrogenesis of rabbit SF-MSCs and can effectively repair cartilage defects through the regeneration of hyaline cartilage.

Repair of osteochondral defects using injectable chitosan-based hydrogel encapsulated synovial fluid-derived mesenchymal stem cells in a rabbit model.

The regeneration of hyaline articular cartilage remains a major challenge due to the limited potential for cartilage to self-repair. Mesenchymal stem cell and hydrogel scaffold-based cartilage tissue engineering is a promising technique for articular cartilage therapy. The purpose of this study was to investigate the use of rabbit synovial fluid mesenchymal stem cells (rbSF-MSCs) encapsulated in an injectable chitosan-based hydrogel to repair full-thickness cartilage defects in femoral patellar grooves in rabbits. The rbSF-MSCs were obtained from rabbit synovial fluid and the surface markers of rbSF-MSCs were coincidental to the identification criteria of MSCs according to flow cytometry. The rbSF-MSCs were able to differentiate into osteogenic, adipogenic and chondrogenic lineages. In the present study, rbSF-MSCs encapsulated in glycol chitosan (GC) and benzaldehyde capped poly (ethylene oxide) (OHC-PEO-CHO) hydrogel were introduced into rabbits to repair articular cartilage defects. The modulus of the hydrogel could be regulated by the concentrations of GC and OHC-PEO-CHO and the hydrogel has a good biocompatibility to rbSF-MSCs. Assessment of in vivo repair indicates using hydrogel/rbSF-MSCs was superior to using the hydrogel scaffold only and the untreated control based on gross appearance and histological grading and evaluation. These preliminary findings suggest using the injectable chitosan-based hydrogel as a scaffold and rbSF-MSCs as seed cells is an alternative for tissue engineering of in vivo treatments for cartilage defects and these rbSF-MSCs allografts may be promising for use in clinical applications.

Pulse electromagnetic fields enhance the repair of rabbit articular cartilage defects with magnetic nano-hydrogel.

Hydrogel is an important scaffold material in regenerative medicine and cartilage tissue engineering. Hydrogel material combined with pulse electromagnetic fields (PEMFs), PEMFs has the potential to manage the repair of defective articular cartilage. Here, we developed a new type of magnetic hydrogel. The data shows that the magnetic hydrogel had good mechanical properties, and its surface had micropores and unevenness, which was conducive to cell adhesion growth. Infrared spectroscopy analysis showed that the magnetic particles were evenly distributed in the hydrogel, and the addition of constant static magnetic field yielded magnetic water. The hydrogel exhibited good superparamagnetism. The co-culture of the magnetic hydrogel and bone marrow mesenchymal stem cells (BMSCs) showed good biocompatibility. The PEMFs promoted the differentiation of the BMSCs into cartilage, and the index of cartilage differentiation increased obviously. The results of the animal experiments showed that the magnetic hydrogel and BMSCs combined with pulsed electromagnetic field had a strong repair effect. They also showed that the magnetic nano-hydrogel combined with the PEMFs induced chondrogenic differentiation of the BMSCs. The positive experimental results suggested that the combination of magnetic hydrogel and the PEMFs can be used as an effective method for repairing articular cartilage defects in rabbit model.

Adaptable Hydrogels Mediate Cofactor-Assisted Activation of Biomarker-Responsive Drug Delivery via Positive Feedback for Enhanced Tissue Regeneration.

The targeted and simultaneous delivery of diverse cargoes with vastly different properties by the same vehicle is highly appealing but challenging. Here, a bioactive nanocomposite hydrogel based on hyaluronic acid and self-assembled pamidronate-magnesium nanoparticles for the localized elution and on-demand simultaneous release of bioactive ions and small molecule drugs is described. The obtained nanocomposite hydrogels exhibit excellent injectability and efficient stress relaxation, thereby allowing easy injection and consequent adaptation of hydrogels to bone defects with irregular shapes. Magnesium ions released from the hydrogels promote osteogenic differentiation of the encapsulated human mesenchymal stem cells (hMSCs) and activation of alkaline phosphatase (ALP). The activated ALP subsequently catalyzes the dephosphorylation (activation) of Dex phosphate, a pro-drug of Dex, and expedites the release of Dex from hydrogels to further promote hMSC osteogenesis. This positive feedback circuit governing the activation and release of Dex significantly enhances bone regeneration at the hydrogel implantation sites. The findings suggest that these injectable nanocomposite hydrogels mediate optimized release of diverse therapeutic cargoes and effectively promote in situ bone regeneration via minimally invasive procedures.

Magnetic-Activated Cell Sorting Strategies to Isolate and Purify Synovial Fluid-Derived Mesenchymal Stem Cells from a Rabbit Model.

Mesenchymal stem cells (MSCs) are the main cell source for cell-based therapy. MSCs from articular cavity synovial fluid could potentially be used for cartilage tissue engineering. MSCs from synovial fluid (SF-MSCs) have been considered promising candidates for articular regeneration, and their potential therapeutic benefit has made them an important research topic of late. SF-MSCs from the knee cavity of the New Zealand white rabbit can be employed as an optimized translational model to assess human regenerative medicine. By means of CD90-based magnetic activated cell sorting (MACS) technologies, this protocol successfully obtains rabbit SF-MSCs (rbSF-MSCs) from this rabbit model and further fully demonstrates the MSC phenotype of these cells by inducing them to differentiate to osteoblasts, adipocytes, and chondrocytes. Therefore, this approach can be applied in cell biology research and tissue engineering using simple equipment and procedures.

Development of Magnetic Nanocomposite Hydrogel with Potential Cartilage Tissue Engineering.

Magnetic nanocomposite hydrogels show high potential to improve tissue engineering. In this study, a magnetic nanocomposite hydrogel was prepared from poly(vinyl alcohol), nano-hydroxyapatite (n-HA), and magnetic nanoparticles (Fe2O3) using the ultrasonic dispersion method and freeze-thaw cross-linking molding. The water content and crystallinity of the magnetic nanocomposite hydrogel were tested. Microscopic morphology assessment, mechanical testing, and characterization were performed. Additionally, the magnetic nanocomposite hydrogel was co-cultured with bone mesenchymal stem cells (BMSCs) to determine its cell compatibility. We found that the magnetic nanocomposite hydrogel had good mechanical properties and that its mechanical properties were enhanced by the addition of n-HA. The BMSCs showed uniform growth on the surface of the magnetic nanocomposite hydrogel and high rates of proliferation. BMSC growth was also enhanced by the addition of Fe2O3 and also significant stimulated chondrocyte-related gene expression. Thus, the magnetic nanocomposite hydrogel scaffold material we describe here could have broad applications in cartilage tissue engineering.

A 3D-Printed PLCL Scaffold Coated with Collagen Type I and Its Biocompatibility.

Scaffolds play an important role in tissue engineering and their structure and biocompatibility have great influence on cell behaviors. In this study, poly(l-lactide-co-ε-caprolactone) (PLCL) scaffolds were printed by a 3D printing technology, low-temperature deposition manufacturing (LDM), and then PLCL scaffolds were treated by alkali and coated with collagen type I (COLI). The scaffolds were characterized by scanning electron microscopy (SEM), porosity test, mechanical test, and infrared spectroscopy. The prepared PLCL and PLCL-COLI scaffolds had three-dimensional (3D) porous structure and they not only have macropores but also have micropores in the deposited lines. Although the mechanical property of PLCL-COLI was slightly lower than that of PLCL scaffold, the hydrophilicity of PLCL-COLI was significantly enhanced. Rabbit articular chondrocytes were extracted and were identified as chondrocytes by toluidine blue staining. To study the biocompatibility, the chondrocytes were seeded on scaffolds for 1, 3, 5, 7, and 10 days. MTT assay showed that the proliferation of chondrocytes on PLCL-COLI scaffold was better than that on PLCL scaffold. And the morphology of cells on PLCL-COLI after 1-day culture was much better than that on PLCL. This 3D-printed PLCL scaffold coated with COLI shows a great potential application in tissue engineering.

Repair of articular cartilage defects with intra-articular injection of autologous rabbit synovial fluid-derived mesenchymal stem cells.

BACKGROUND: The role of rabbit synovial fluid-derived mesenchymal stem cells (rbSF-MSCs) in cartilage defect repair remains undefined. This work evaluates the in vivo effects of rbSF-MSCs to repair knee articular cartilage defects in a rabbit model. METHODS: Cartilage defects were made in the patellar grooves of New Zealand white rabbits. The rbSF-MSCs were generated from the knee cavity by arthrocentesis. Passage 5 rbSF-MSCs were assayed by flow cytometry. The multipotency of rbSF-MSCs was confirmed after 3 weeks induction in vitro and the autologous rbSF-MSCs and predifferentiated rbSF-MSCs were injected into the synovial cavity. The intra-articular injection was performed once a week for 4 weeks. The animals were euthanized and the articular surfaces were subjected to macroscopic and histological evaluations at 8 and 12 weeks after the first intra-articular injection. RESULTS: Hyaline-like cartilage was detected in the defects treated with rbSF-MSCs, while fibrocartilage tissue formed in the defects treated with chondrocytes induced from rbSF-MSCs. CONCLUSIONS: Our results suggest that autologous undifferentiated rbSF-MSCs are favorable to articular cartilage regeneration in treating cartilage defects.

Preparation and biocompatibility of diphasic magnetic nanocomposite scaffold.

We describe the study of a new type of diphasic magnetic nanocomposite scaffold (PLGA/Col-I-PLGA/n-HA/Fe2O3) and its preparation using a novel low-temperature deposition manufacturing (LDM) technology. In order to study the biocompatibility of this scaffold, we evaluated and explored its feasibility as a scaffold for tissue engineering. Diphasic magnetic nanocomposite scaffolds (PLGA/Col-I-PLGA/n-HA/Fe2O3) were prepared using LDM technology. The mechanical properties of the scaffold were tested using an electronic testing machine, electron microscopy was utilized to observe the ultrastructure, and a medium (ethanol) immersion method was used to determine the porosity of the scaffold. The scaffold was co-cultured with bone mesenchymal stem cells (BMSCs) and was induced to differentiate. The biocompatibility of the scaffold was then tested. The mechanical test results of the diphasic magnetic nanocomposite scaffold demonstrated good mechanical properties. Electron microscopy studies revealed two layers of pore sizes each with a uniform distribution, with the upper cartilage pore size observed to be small while the middle continuous phase was found to be in a good integration. Pore size and porosity test results demonstrated a cartilage layer pore size of 186 µm, with a porosity measured to be 89.5%. The pore size and porosity of the bone layer were 394 µm and 86.1%, respectively. These properties met the design requirements of double layer scaffolds. Co-culture of the diphasic magnetic nanocomposite scaffold and bone mesenchymal stem cells (BMSCs) exhibited good proliferation of bone mesenchymal stem cells (BMSCs), and the scaffold was found to be able to promote differentiation of the differentiation-oriented cells. These results demonstrated a good biocompatibility of the diphasic magnetic nanocomposite scaffold. The diphasic magnetic nanocomposite scaffold (PLGA/Col-I-PLGA/n-HA/Fe2O3) was found to have suitable mechanical properties as well as cell compatibility. The measured pore size and porosity met the requirements for cell adhesion and cell growth, which matched more closely to that of the physiological structure of normal articular cartilage and subchondral bones. We expect this to represent new technology for improved repair of cartilage and subchondral bone lesions caused by osteoarthritis or trauma.

Functional peptides for cartilage repair and regeneration.

Cartilage repair after degeneration or trauma continues to be a challenge both in the clinic and for scientific research due to the limited regenerative capacity of this tissue. Cartilage tissue engineering, involving a combination of cells, scaffolds, and growth factors, is increasingly used in cartilage regeneration. Due to their ease of synthesis, robustness, tunable size, availability of functional groups, and activity, peptides have emerged as the molecules with the most potential in drug development. A number of peptides have been engineered to regenerate cartilage by acting as scaffolds, functional molecules, or both. In this paper, we will summarize the application of peptides in cartilage tissue engineering and discuss additional possibilities for peptides in this field.

Isolation and characterization of human mesenchymal stem cells derived from synovial fluid by magnetic-activated cell sorting (MACS).

Mesenchymal stem cells (MSCs) are the primary source of cells used for cell-based therapy in tissue engineering. MSCs are found in synovial fluid, a source that could be conveniently used for cartilage tissue engineering. However, the purification and characterization of SF-MSCs has been poorly documented in the literature. Here, we outline an easy-to-perform approach for the isolation and culture of MSCs derived from human synovial fluid (hSF-MSCs). We have successfully purified hSF-MSCs using magnetic-activated cell sorting (MACS) using the MSC surface marker, CD90. Purified SF-MSCs demonstrate significant renewal capacity following several passages in culture. Furthermore, we demonstrated that MACS-sorted CD90+ cells could differentiated into osteoblasts, adipocytes, and chondrocytes in vitro. In addition, we show that these cells can generate cartilage tissue in micromass culture as well. This study demonstrates that MACS is a useful tool that can be used for the purification of hSF-MSCs from synovial fluid. The proliferation properties and ability to differentiate into chondrocytes make these hSF-MSCs a promising source of stem cells for applications in cartilage repair.

TGFß1 induces hypertrophic change and expression of angiogenic factors in human chondrocytes.

The transforming growth factor ß1 (TGFß1) plays an important role in cartilage development. However, whether TGFß1 stimulates chondrocyte proliferation and cartilage regeneration in osteoarthritis (OA) remains elusive, especially in the context of different treatment and tissue environments. In the present study, we investigated the role of TGFß1 in human chondrocyte culture in vitro, focusing on the morphological change of chondrocytes and the expression of angiogenic factors upon TGFß1 stimulation. We found increased expression of biomarkers indicating chondrocyte hypertrophy and the chondrocytes aggregated to form networks when they were treated with TGFß1. DNA microarray analysis revealed significantly increased expression of genes related to blood vessel formation in TGFß1 treatment group compared to control group. Matrigel assay further demonstrated that chondrocytes had the potential to form network-like structure. These results suggested that TGFß1 induces the hypertrophic change of chondrocytes culture in vitro and induce expression of angiogenic biomarkers. Therefore, application of TGFß1 for chondrocyte culture in practice should be considered prudentially and targeting TGFß1 or relevant receptors to block the signaling pathway might be a strategy to prevent or alleviate progression of osteoarthritis.