Osteochondral Defects Research Articles

Strontium/Silicon/Calcium-Releasing Hierarchically Structured 3D-Printed Scaffolds Accelerate Osteochondral Defect Repair.

Articular cartilage defects are a global challenge, causing substantial disability. Repairing large defects is problematic, often exceeding cartilage's self-healing capacity and damaging bone structures. To tackle this problem, a scaffold-mediated therapeutic ion delivery system is developed. These scaffolds are constructed from poly(ε-caprolactone) and strontium (Sr)-doped bioactive nanoglasses (SrBGn), creating a unique hierarchical structure featuring macropores from 3D printing, micropores, and nanotopologies due to SrBGn integration. The SrBGn-embedded scaffolds (SrBGn-µCh) release Sr, silicon (Si), and calcium (Ca) ions, which improve chondrocyte activation, adhesion, proliferation, and maturation-related gene expression. This multiple ion delivery significantly affects metabolic activity and maturation of chondrocytes. Importantly, Sr ions may play a role in chondrocyte regulation through the Notch signaling pathway. Notably, the scaffold's structure and topological cues expedite the recruitment, adhesion, spreading, and proliferation of chondrocytes and bone marrow-derived mesenchymal stem cells. Si and Ca ions accelerate osteogenic differentiation and blood vessel formation, while Sr ions enhance the polarization of M2 macrophages. The findings show that SrBGn-µCh scaffolds accelerate osteochondral defect repair by delivering multiple ions and providing structural/topological cues, ultimately supporting host cell functions and defect healing. This scaffold holds great promise for osteochondral repair applications.

Cytokine Receptor-like Factor 1 (CRLF1) and Its Role in Osteochondral Repair.

Since cytokine receptor-like factor 1 (CRLF1) has been implicated in tissue regeneration, we hypothesized that CRLF1 released by mesenchymal stem cells can promote the repair of osteochondral defects. The degree of a femoral osteochondral defect repair in rabbits after intra-articular injections of bone marrow-derived mesenchymal stem cells (BMSCs) that were transduced with empty adeno-associated virus (AAV) or AAV containing CRLF1 was determined by morphological, histological, and micro computer tomography (CT) analyses. The effects of CRLF1 on chondrogenic differentiation of BMSCs or catabolic events of interleukin-1beta-treated chondrocyte cell line TC28a2 were determined by alcian blue staining, gene expression levels of cartilage and catabolic marker genes using real-time PCR analysis, and immunoblot analysis of Smad2/3 and STAT3 signaling. Intra-articular injections of BMSCs overexpressing CRLF1 markedly improved repair of a rabbit femoral osteochondral defect. Overexpression of CRLF1 in BMSCs resulted in the release of a homodimeric CRLF1 complex that stimulated chondrogenic differentiation of BMSCs via enhancing Smad2/3 signaling, whereas the suppression of CRLF1 expression inhibited chondrogenic differentiation. In addition, CRLF1 inhibited catabolic events in TC28a2 cells cultured in an inflammatory environment, while a heterodimeric complex of CRLF1 and cardiotrophin-like Cytokine (CLC) stimulated catabolic events via STAT3 activation. A homodimeric CRLF1 complex released by BMSCs enhanced the repair of osteochondral defects via the inhibition of catabolic events in chondrocytes and the stimulation of chondrogenic differentiation of precursor cells.

Talus Osteochondral Defect Treatment With Biological Scaffold.

Talus Osteochondral defects (OCDs) are challenging and there is no consensus in literature regarding which is the best method of treatment. New techniques coming from regenerative medicine are being considered good alternatives of treatment and are being used exponentially in orthopaedic surgery. Platelet-rich fibrin (PRF) is the second generation of platelet concentrates. It has a convenient method of acquisition and can be used to create a biological scaffold which is able to seal up cavitary lesions. In this article, the authors describe a talus OCD treated with a biological scaffold, reporting the technique details and its results clinical and radiological results. The case report objective is to portray the use of this kind of biological material, its advantages, and limitations.Level of Evidence: Level 5.

An Encapsulation-Free and Hierarchical Porous Triboelectric Scaffold with Dynamic Hydrophilicity for Efficient Cartilage Regeneration.

Tissue engineering and electrotherapy are two promising methods to promote tissue repair. However, their integration remains an underexplored area, because their requirements on devices are usually distinct. Triboelectric nanogenerators (TENGs) have shown great potential to develop self-powered devices. However, due to their susceptibility to moisture, TENGs have to be encapsulated in vivo. Therefore, existing TENGs cannot be employed as tissue engineering scaffolds, which require direct interaction with surrounding cells. Here, the concept of triboelectric scaffolds (TESs) is proposed. Poly(glycerol sebacate), a biodegradable and relatively hydrophobic elastomer, is selected as the matrix of TESs. Each hydrophobic micropore in multi-hierarchical porous TESs efficiently serves as a moisture-resistant working unit of TENGs. Integration of tons of micropores ensures the electrotherapy ability of TESs in vivo without encapsulation. Originally hydrophobic TESs are degraded by surface erosion and transformed into hydrophilic surfaces, facilitating their role as tissue engineering scaffolds. Notably, TESs seeded with chondrocytes obtain dense and large matured cartilages after subcutaneous implantation in nude mice. Importantly, rabbits with osteochondral defects receiving TES implantation show favorable hyaline cartilage regeneration and complete cartilage healing. This work provides a promising electronic biomedical device and will inspire a series of new in vivo applications.

Hyaluronic Acid‐based Cell‐free Composite Scaffold Promotes Osteochondral Repair In Vitro by Upregulating Osteogenic‐ and Chondrogenic‐Specific Gene Expressions

Osteochondral defects pose a significant challenge in clinical practice, leading to increased medical care, diminished quality of life for patients, and elevated economic burden. The restoration of osteochondral defects, particularly in cartilage, is limited by its finite repair capacity and complex architecture. Treatment based on regenerative therapies acclaims the favorable alternative to contemporary procedures. Studies reveal that engineered biomaterials hold the significant importance in stimulating tissue repair with minimal cost and risks. In this study, a porous composite scaffold is developed, where host cells infiltrate and create the microenvironment for cellular adhesion and enhanced differentiation. Thus, a composite scaffold composed of natural glycosaminoglycan hyaluronic acid (HA), the protein component fibrin, bioceramic nanohydroxyapatite (nHAP), and graphene oxide (GO) is fabricated. Scanning electron microscopy observation and physiochemical characterization reveal an interconnected pore structure, optimum swelling potential, high porosity (80.14%), controlled biodegradation, high mechanical properties, and mineralization. Evaluation of scaffold's biocompatibility using osteoblast – like MG‐63 cells – shows adequate viability, cell adhesion, and osteoinductive potential. The upregulated expressions of osteogenic and chondrogenic genes OCN, ALP, COL1A1, ACAN, SOX9, and COL2A1 promote mineralization and extracellular matrix formation. These findings suggest that the composite scaffold HA‐GO‐F‐nHAP exhibits promising potential for osteochondral repair.

Architecture of β-lactoglobulin coating modulates bioinspired alginate dialdehyde-gelatine/polydopamine scaffolds for subchondral bone regeneration

In this study, we developed polydopamine (PDA)-functionalized alginate dialdehyde-gelatine (ADA-GEL) scaffolds for subchondral bone regeneration. These polymeric scaffolds were then coated with β-Lactoglobulin (β-LG) at concentrations of 1 mg/ml and 2 mg/ml. Morphological analysis indicated a homogeneous coating of the β-LG layer on the surface of network-like scaffolds. The β-LG-coated scaffolds exhibited improved swelling capacity as a function of the β-LG concentration. Compared to ADA-GEL/PDA scaffolds, the β-LG-coated scaffolds demonstrated delayed degradation and enhanced biomineralization. Here, a lower concentration of β-LG showed long-lasting stability and superior biomimetic hydroxyapatite mineralization. According to the theoretical findings, the single-state, representing the low concentration of β-LG, exhibited a homogeneous distribution on the surface of the PDA, while the dimer-state (high concentration) displayed a high likelihood of uncontrolled interactions. β-LG-coated ADA-GEL/PDA scaffolds with a lower concentration of β-LG provided a biocompatible substrate that supported adhesion, proliferation, and alkaline phosphatase (ALP) secretion of sheep bone marrow mesenchymal stem cells, as well as increased expression of osteopontin (SPP1) and collagen type 1 (COL1A1) in human osteoblasts. These findings indicate the potential of protein-coated scaffolds for subchondral bone tissue regeneration. Statement of SignificanceThis study addresses a crucial aspect of osteochondral defect repair, emphasizing the pivotal role of subchondral bone regeneration. The development of polydopamine-functionalized alginate dialdehyde-gelatine (ADA-GEL) scaffolds, coated with β-Lactoglobulin (β-LG), represents a novel approach to potentially enhance subchondral bone repair. β-LG, a milk protein rich in essential amino acids and bioactive peptides, is investigated for its potential to promote subchondral bone regeneration. This research explores computationally and experimentally the influence of protein concentration on the ordered or irregular deposition, unravelling the interplay between coating structure, scaffold properties, and in-vitro performance. This work contributes to advancing ordered protein coating strategies for subchondral bone regeneration, providing a biocompatible solution with potential implications for supporting subsequent cartilage repair.

Orthobiologics in knee osteoarthritis, dream or reality?

AbstractCartilage restoration or repair, also known as orthobiologic therapy, is indicated after the failure of conservative or supportive treatment. However, there is paucity in evidence supporting the efficacy of orthobiologic therapy. The blood-derived products, such as platelet-rich plasma (PRP), is one of the commonly used orthobiologic therapy for knee osteoarthritis. Several studies have shown that PRP is superior to other treatments, but the anatomic changes are scarce. Treatment with mesenchymal stem cells (MSCs) offers the greatest potential for curing degenerative disease due to their self-renewal ability, ability to migrate towards injured tissues (homing/trafficking), and ability to promote repair and regeneration of osteochondral defects. However, ethical concerns and high costs remain major challenges associated with MSC therapy. Gene therapy, another promising orthobiologic therapy, is currently in phase II clinical trial and has shown promising results. The key factors for successful orthobiologic therapy include patient selection, appropriate dosing, treatment of underlying mechanical problems, age, severity, and cost-effectiveness.

A Hybrid Scaffold Induces Chondrogenic Differentiation and Enhances In Vivo Cartilage Regeneration.

Extensively researched tissue engineering strategies involve incorporating cells into suitable biomaterials, offering promising alternatives to boost tissue repair. In this study, a hybrid scaffold, Gel-DCM, which integrates a photoreactive gelatin-hyaluronic acid hydrogel (Gel) with an oriented porous decellularized cartilage matrix (DCM), was designed to facilitate chondrogenic differentiation and cartilage repair. The Gel-DCM exhibited excellent biocompatibility in vitro, promoting favorable survival and growth of human adipose-derived stem cells (hADSCs) and articular chondrocytes (hACs). Gene expression analysis indicated that the hACs expanded within the Gel-DCM exhibited enhanced chondrogenic phenotype. In addition, Gel-DCM promoted chondrogenesis of hADSCs without the supplementation of exogenous growth factors. Following this, invivo experiments were conducted where empty Gel-DCM or Gel-DCM loaded with hACs/hADSCs were used and implanted to repair osteochondral defects in a rat model. In the control group, no implants were delivered to the injury site. Interestingly, macroscopic, histological, and microcomputed tomography scanning results revealed superior cartilage restoration and subchondral bone reconstruction in the empty Gel-DCM group compared with the control group. Moreover, both hACs-loaded and hADSCs-loaded Gel-DCM implants exhibited superior repair of hyaline cartilage and successful reconstruction of subchondral bone, whereas defects in the control groups were predominantly filled with fibrous tissue. These observations suggest that the Gel-DCM can provide an appropriate three-dimensional chondrogenic microenvironment, and its combination with reparative cell sources, ACs or ADSCs, holds great potential for facilitating cartilage regeneration.

HWJMSC-EVs promote cartilage regeneration and repair via the ITGB1/TGF-β/Smad2/3 axis mediated by microfractures

The current first-line treatment for repairing cartilage defects in clinical practice is the creation of microfractures (MF) to stimulate the release of mesenchymal stem cells (MSCs); however, this method has many limitations. Recent studies have found that MSC-derived extracellular vesicles (MSC-EVs) play an important role in tissue regeneration. This study aimed to verify whether MSC-EVs promote cartilage damage repair mediated by MFs and to explore the repair mechanisms. In vitro experiments showed that human umbilical cord Wharton’s jelly MSC-EVs (hWJMSC-EVs) promoted the vitality of chondrocytes and the proliferation and differentiation ability of bone marrow-derived MSCs. This was mainly because hWJMSC-EVs carry integrin beta-1 (ITGB1), and cartilage and bone marrow-derived MSCs overexpress ITGB1 after absorbing EVs, thereby activating the transforming growth factor-β/Smad2/3 axis. In a rabbit knee joint model of osteochondral defect repair, the injection of different concentrations of hWJMSC-EVs into the joint cavity showed that a concentration of 50 µg/ml significantly improved the formation of transparent cartilage after MF surgery. Extraction of regenerated cartilage revealed that the changes in ITGB1, transforming growth factor-β, and Smad2/3 were directly proportional to the repair of regenerated cartilage. In summary, this study showed that hWJMSC-EVs promoted cartilage repair after MF surgery.Graphical abstract

In vitro and in vivo evaluation of periosteum-derived cells and iPSC-derived chondrocytes encapsulated in GelMA for osteochondral tissue engineering.

Osteochondral defects are deep joint surface lesions that affect the articular cartilage and the underlying subchondral bone. In the current study, a tissue engineering approach encompassing individual cells encapsulated in a biocompatible hydrogel is explored in vitro and in vivo. Cell-laden hydrogels containing either human periosteum-derived progenitor cells (PDCs) or human induced pluripotent stem cell (iPSC)-derived chondrocytes encapsulated in gelatin methacryloyl (GelMA) were evaluated for their potential to regenerate the subchondral mineralized bone and the articular cartilage on the joint surface, respectively. PDCs are easily isolated and expanded progenitor cells that are capable of generating mineralized cartilage and bone tissue in vivo via endochondral ossification. iPSC-derived chondrocytes are an unlimited source of stable and highly metabolically active chondrocytes. Cell-laden hydrogel constructs were cultured for up to 28 days in a serum-free chemically defined chondrogenic medium. On day 1 and day 21 of the differentiation period, the cell-laden constructs were implanted subcutaneously in nude mice to evaluate ectopic tissue formation 4 weeks post-implantation. Taken together, the data suggest that iPSC-derived chondrocytes encapsulated in GelMA can generate hyaline cartilage-like tissue constructs with different levels of maturity, while using periosteum-derived cells in the same construct type generates mineralized tissue and cortical bone in vivo. Therefore, the aforementioned cell-laden hydrogels can be an important part of a multi-component strategy for the manufacturing of an osteochondral implant.

Trilayered biomimetic hydrogel scaffolds with dual-differential microenvironment for articular osteochondral defect repair

Commonly, articular osteochondral tissue exists significant differences in physiological architecture, mechanical function, and biological microenvironment. However, the development of biomimetic scaffolds incorporating upper cartilage, middle tidemark-like, and lower subchondral bone layers for precise articular osteochondral repair remains elusive. This study proposed here a novel strategy to construct the trilayered biomimetic hydrogel scaffolds with dual-differential microenvironment of both mechanical and biological factors. The cartilage-specific microenvironment was achieved through the grafting of kartogenin (KGN) into gelatin via p-hydroxyphenylpropionic acid (HPA)-based enzyme crosslinking reaction as the upper cartilage layer. The bone-specific microenvironment was achieved through the grafting of atorvastatin (AT) into gelatin via dual-crosslinked network of both HP-based enzyme crosslinking and glycidyl methacrylate (GMA)-based photo-crosslinking reactions as the lower subchondral bone layer. The introduction of tidemark-like middle layer is conducive to the formation of well-defined cartilage-bone integrated architecture. The in vitro experiments demonstrated the significant mechanical difference of three layers, successful grafting of drugs, good cytocompatibility and tissue-specific induced function. The results of in vivo experiments also confirmed the mechanical difference of the trilayered bionic scaffold and the ability of inducing osteogenesis and chondrogenesis. Furthermore, the articular osteochondral defects were successfully repaired using the trilayered biomimetic hydrogel scaffolds by the activation of endogenous recovery, which offers a promising alternative for future clinical treatment.

The Windshield Wiper Sign Is an Instability-Related Osteochondral Defect of the Anterolateral Femoral Head

PurposeTo investigate a radiographic sign believed to be indicative of hip instability and acetabular suction seal disruption in the native hip, coined the “windshield wiper” (WSW) sign. Materials and MethodsA retrospective review was performed for patients who underwent periacetabular osteotomy (PAO) with the senior author between March 2021 and September 2023. A WSW sign was identified on plain films as a concave or flat osteochondral defect on the anterolateral femoral head extending medial to the head-neck junction with resultant loss of femoral head sphericity in the native hip. Every patient underwent a standardized series of radiographs, as well as computed tomography and magnetic resonance imaging. All patients underwent arthroscopy prior to PAO to address intra-articular pathology and other indicated procedures. The osteochondral defect and resultant suction seal disruption were verified during arthroscopy. These patients were then compared with a control group of arthroscopically treated hips without hip instability. ResultsOf 250 patients reviewed, a total of 19 hips in 17 patients (prevalence of 7.6%) demonstrated radiographic evidence of the WSW sign. All patients with a WSW sign presented with symptomatic clinical hip instability requiring a PAO. The mean patient age was 31.2 years, with a mean lateral center edge angle (LCEA) of 14.3 degrees. There were 13 hips (68.4%) with dysplasia, 4 (21.1%) with borderline dysplasia, and 2 (10.5%) with a normal LCEA. All patients with a WSW sign and LCEA ≥20° displayed significant femoral antetorsion abnormalities. All arthroscopic videos and images demonstrated a compromised suction seal. Of the 50 control group hips reviewed, the WSW sign was not identified. ConclusionsThe WSW sign is an uncommon radiographic finding in patients with hip instability. When identified, it can be predictive of substantial instability, especially in cases which are otherwise considered borderline dysplasia or normal based on LCEA. Level of EvidenceIII, case-control study

Osteochondral Allograft Transplantation for the Treatment of an Acetabular Defect: A Case Report.

A 20-year-old woman presented with a unipolar, 1.8 × 1.8-cm osteochondral defect of the left acetabulum. Osteochondral allograft transplantation was performed using a medial tibial plateau allograft resulting in excellent clinical outcomes across 4 different outcome scores and maintenance of the joint space at 4.3 years postoperatively. Although previous literature has demonstrated long-term clinical success of osteochondral allograft transplantation in knee, excellent clinical outcomes can also be obtained in the hip. Thus, osteochondral allograft transplantation may be a viable treatment option for adolescents and young adults with concomitant cartilage and subchondral bone hip defects.

Regenerative capacity of morselized cartilage in vitro and in an osteochondral defect model

IntroductionNumerous treatment modalities for focal articular cartilage defects exist, including the use of chondrons from minced cartilage morsels. However, the use of consistent and reproducible morsel sizes to heal these lesions, especially with a recently characterized alginate-Nanocellulose (NC) hydrogel scaffold, has not been investigated. MethodsCartilage was harvested and morselized into 0.5mm, 1.0mm, and 5.0mm diameters, and cultured. Cell viability and chondrogenic gene expression was analyzed. 0.5mm diameter minced cartilage morsels were harvested and used to produce the implant paste. The NC paste was filled into a rabbit articular cartilage defect, and histology was used to assess cartilage repair. ResultsChondrocyte viability of the morsels was highly maintained. Chondrogenic and proliferative genes like ACAN, COL2, COMP, PCNA, SOX9, and PRG4 all increased expression to a varying degree as morsel size decreased. 0.5mm morsels exhibited the highest chondrogenic potential. Also, NC paste containing 0.5mm morsels resulted in complete defect closure unlike marrow stimulation alone. Safranin-O staining demonstrated superior cartilage formation in the defect area. DiscussionSmaller consistent morsel size was found to be linked to increased chondrogenic potential, as hypothesized. However, since PRG4 expression was highest in 1mm morsels and MMP-13 gene expression was significantly decreased in only 0.5mm morsels, this demonstrates the need to adjust morsel size to optimize gene expression of interest. NC paste mixed with 0.5mm morsels produced the greatest regenerative capacity. Exploring the regenerative potential of unique hydrogels and chondron morsel sizes is warranted to provide insight on optimizing clinical implants to improve patient recovery.

Participation in Sports or Recreational Activities After Osteochondral Allograft Transplantation of the Talus

Background: Fresh osteochondral allograft (OCA) transplantation is a viable treatment option for osteochondral defects of the talus. However, sufficient data are not available on patients’ participation in sports or recreational activities after the procedure. Purpose: To assess whether patients undergoing OCA transplantation of the talus participated in sports or recreational activities postoperatively. Study Design: Case series; level of evidence, 4. Methods: A total of 36 ankles in 34 patients underwent OCA transplantation of the talus. At a mean follow-up of 9.2 years, information on participation in sports or recreational activities pre- and postoperatively was obtained, as well as postoperative pain, function, and satisfaction. Results: The mean age at the time of surgery was 36.1 years (range, 20.5-57.7 years), and 50% of patients were men. The mean graft size was 3.6 cm2 (range, 1-7.2 cm2) or 41.1% of the talar dome. Before the injury, 63.9% of patients (23/36 ankles) reported being highly competitive athletes or well trained and frequently sporting; 36.1% of patients (13/36 ankles) reported sometimes sporting or were nonsporting. Also, 66.7% of patients (24/36 ankles) were able to participate in sports or recreational activities after OCA transplantation and 50% (18/36 ankles) were still participating in sports or recreational activities at the latest follow-up. In a subset of well-trained or highly competitive athletes, 73.9% (17/23 ankles) were able to return to sports or recreational activities at any point after OCA transplantation, and 65.2% (15/23 ankles) were still participating at the latest follow-up. Further surgery occurred in 16.7% of patients (6/36 ankles). Graft survivorship was 94.3% at 5 years and 85.3% at 10 years. There was a significant improvement in the mean Olerud-Molander Ankle Scores, and the mean Foot and Ankle Ability Measure scores were high postoperatively. Moreover, 79.4% of patients (27/34 ankles) were either satisfied or extremely satisfied with the allograft surgery. Conclusion: Fresh OCA transplantation is a reasonable surgical option for osteochondral defects of the talus for young, active patients who have failed previous operative management or have massive defects.

Magnetic resonance imaging combined with histological evaluation of repair process using the microfracture technique in an association of osteocartilaginous and meniscal surgically induced lesions of the knee. In vivo experiment on a rabbit model.

The present research study aimed to assess magnetic resonance imaging (MRI) changes and histological findings in the therapeutic effects of microfractures in the treatment of complex animal knee lesions resulting from osteochondral and meniscal defects resulting from non-total meniscectomies. The anterior cruciate ligament lesions are also proven to facilitate the development of osteoarthritis in the knee and worsen the prognosis. Surgery was performed on the right knee joint of 22 male rabbits in order to partially remove the anterior horn of the internal meniscus and to induce an osteochondral defect at the level of the internal femoral condyle. The induced lesion complex was aimed to simulate a clinical situation that occurs frequently in orthopedic practice when young adults undergo partial meniscectomy and at the time of surgery, an osteochondral defect is diagnosed. Rabbits were separated into two study groups: the control (C1) group and the microfractures (MF2) group. After the induced cartilage defect and partial meniscectomy, both groups were followed-up for six months using detailed MRI. Also, anatomical specimens were histologically analyzed to show modifications and signs of healing process, along with complications, in the study group. The results showed that the microfracture group had better results concerning articular surface defect healing in comparison to the control group. Our results suggest that microfractures do improve results concerning surface contact healing and serial MRI studies can be useful in observing the remodeling process in dynamics.

A comparative analysis of 3D bioprinted gelatin-hyaluronic acid-alginate scaffold and microfracture for the management of osteochondral defects in the rabbit knee joint.

This study aims to compare the radiological, biomechanical, and histopathological results of microfracture treatment and osteochondral damage repair treatment with a new scaffold product produced by the three-dimensional (3D) bioprinting method containing gelatin-hyaluronic acid-alginate in rabbits with osteochondral damage. A new 3D bioprinted scaffold consisting of gelatin, hyaluronic acid, and alginate designed by us was implanted into the osteochondral defect created in the femoral trochlea of 10 rabbits. By randomization, it was determined which side of 10 rabbits would be repaired with a 3D bioprinted scaffold, and microfracture treatment was applied to the other knees of the rabbits. After six months of follow-up, the rabbits were sacrificed. The results of both treatment groups were compared radiologically, biomechanically, and histopathologically. None of the rabbits experienced any complications. The magnetic resonance imaging evaluation showed that all osteochondral defect areas were integrated with healthy cartilage in both groups. There was no significant difference between the groups in the biomechanical load test (p=0.579). No statistically significant difference was detected in the histological examination using the modified Wakitani scores (p=0.731). Our study results showed that 3D bioprinted scaffolds exhibited comparable radiological, biomechanical, and histological properties to the conventional microfracture technique for osteochondral defect treatment.

ICA/SDF-1α/PBMSCs loaded onto alginate and gelatin cross-linked scaffolds promote damaged cartilage repair.

A three-dimensional alginate-coated scaffold (GAIS) was constructed in the present study to showcase the multidifferentiation potential of peripheral blood mesenchymal stem cells (PBMSCs) and to investigate the role and mechanism by which Icariin (ICA)/stromal cell-derived factor (SDF-1α)/PBMSCs promote damaged articular repair. In addition, the ability of ICA, in combination with SDF-1α, to promote the migration and proliferation of stem cells was validated through the utilization of CCK-8 and migration experiments. The combination of ICA and SDF-1α inhibited the differentiation of PBMSCs into cartilage, as demonstrated by invivo experiments and histological staining. Both PCR and western blot experiments showed that GAIS could upregulate the expression of particular genes in chondrocytes. In comparison to scaffolds devoid of alginate (G0), PBMSCs seeded into GAIS scaffolds exhibited a greater rate of proliferation, and the conditioned medium derived from scaffolds containing SDF-1α enhanced the capacity for cell migration. Moreover, after a 12-week treatment period, GAIS, when successfully transplanted into osteochondral defects of mice, was found to promote cartilage regeneration and repair. The findings, therefore, demonstrate that GAIS enhanced the invitro capabilities of PBMSCs, including proliferation, migration, homing and chondrogenic differentiation. In addition, ICA and SDF-1α effectively collaborated to support cartilage formation invivo. Thus, the ICA/SDF-1α/PBMSC-loaded biodegradable alginate-gelatin scaffolds showcase considerable potential for use in cartilage repair.

Locally Directed Recombinant Adeno- Associated Virus–Mediated IGF-1 Gene Therapy Enhances Osteochondral Repair and Counteracts Early Osteoarthritis In Vivo

Background: Restoration of osteochondral defects is critical, because osteoarthritis (OA) can arise. Hypothesis: Overexpression of insulin-like growth factor 1 (IGF-1) via recombinant adeno-associated viral (rAAV) vectors (rAAV-IGF-1) would improve osteochondral repair and reduce parameters of early perifocal OA in sheep after 6 months in vivo. Study Design: Controlled laboratory study. Methods: Osteochondral defects were created in the femoral trochlea of adult sheep and treated with rAAV-IGF-1 or rAAV-lacZ (control) (24 defects in 6 knees per group). After 6 months in vivo, osteochondral repair and perifocal OA were assessed by well-established macroscopic, histological, and immunohistochemical scoring systems as well as biochemical and micro–computed tomography evaluations. Results: Application of rAAV-IGF-1 led to prolonged (6 months) IGF-1 overexpression without adverse effects, maintaining a significantly superior overall cartilage repair, together with significantly improved defect filling, extracellular matrix staining, cellular morphology, and surface architecture compared with rAAV-lacZ. Expression of type II collagen significantly increased and that of type I collagen significantly decreased. Subchondral bone repair and tidemark formation were significantly improved, and subchondral bone plate thickness and subarticular spongiosa mineral density returned to normal. The OA parameters of perifocal structure, cell cloning, and matrix staining were significantly better preserved upon rAAV-IGF-1 compared with rAAV-lacZ. Novel mechanistic associations between parameters of osteochondral repair and OA were identified. Conclusion: Local rAAV-mediated IGF-1 overexpression enhanced osteochondral repair and ameliorated parameters of perifocal early OA. Clinical Relevance: IGF-1 gene therapy may be beneficial in repair of focal osteochondral defects and prevention of perifocal OA.

Effect of Passaging on Bovine Chondrocyte Gene Expression and Engineered Cartilage Production.

Tissue engineering strategies show great potential for repairing osteochondral defects in osteoarthritic joints; however, these approaches often rely on passaging cells multiple times to obtain enough cells to produce functional tissue. Unfortunately, monolayer expansion culture causes chondrocyte dedifferentiation, which is accompanied by a phenotypical and morphological shift in chondrocyte properties that leads to a reduction in the quality of de novo cartilage produced. Thus, the objective of this study was to evaluate transcriptional variations during in vitro expansion culture and determine how differences in cell phenotype from monolayer expansion alter development of functional engineered cartilage. We used an unbiased approach to explore genome-wide transcriptional differences in chondrocyte phenotype at passage 1 (P1), P3, and P5, and then seeded cells into hydrogel scaffolds at P3 and P5 to assess cells' abilities to produce cartilaginous extracellular matrix in three dimensional (3D). We identified distinct phenotypic differences, specifically for genes related to extracellular organization and cartilage development. Both P3 and P5 chondrocytes were able to produce chondrogenic tissue in 3D, with P3 cells producing matrix with greater compressive properties and P5 cells secreting matrix with higher glycosaminoglycan/DNA and collagen/DNA ratios. Furthermore, we identified 24 genes that were differentially expressed with passaging and enriched in human osteoarthritis (OA) genome-wide association studies, thereby prioritizing them as functionally relevant targets to improve protocols that recapitulate functional healthy cartilage with cells from adult donors. Specifically, we identified novel genes, such as TMEM190 and RAB11FIP4, which were enriched with human hip OA and may play a role in chondrocyte dedifferentiation. This work lays the foundation for several pathways and genes that could be modulated to enhance the efficacy for chondrocyte culture for tissue regeneration, which could have transformative impacts for cell-based cartilage repair strategies.