Anti-hypertrophic effect of synovium-derived stromal cells on costal chondrocytes promotes cartilage repairs

Enhanced articular cartilage regeneration using costal chondrocyte-derived scaffold-free tissue engineered constructs with ascorbic acid treatment

Background

Cartilage tissue engineering faces challenges related to the use of scaffolds and limited seed cells. This study aims to propose a cost-effective and straightforward approach using costal chondrocytes (CCs) as an alternative cell source to overcome these challenges, eliminating the need for special culture equipment or scaffolds.

Methods

CCs were cultured at a high cell density with and without ascorbic acid treatment, serving as the experimental and control groups, respectively. Viability and tissue-engineered constructs (TEC) formation were evaluated until day 14. Slices of TEC samples were used for histological staining to evaluate the secretion of glycosaminoglycans and different types of collagen proteins within the extracellular matrix. mRNA sequencing and qPCR were performed to examine gene expression related to cartilage matrix secretion in the chondrocytes. In vivo experiments were conducted by implanting TECs from different groups into the defect site, followed by sample collection after 12 weeks for histological staining and scoring to evaluate the extent of cartilage regeneration. Hematoxylin-eosin (HE), Safranin-O-Fast Green, and Masson's trichrome stainings were used to examine the content of cartilage-related matrix components in the in vivo repair tissue. Immunohistochemical staining for type I and type II collagen, as well as aggrecan, was performed to assess the presence and distribution of these specific markers. Additionally, immunohistochemical staining for type X collagen was used to observe any hypertrophic changes in the repaired tissue.

Results

Viability of the chondrocytes remained high throughout the culture period, and the TECs displayed an enriched extracellular matrix suitable for surgical procedures. In vitro study revealed glycosaminoglycan and type II collagen production in both groups of TEC, while the TEC matrix treated with ascorbic acid displayed greater abundance. The results of mRNA sequencing and qPCR showed that genes related to cartilage matrix secretion such as Sox9, Col2, and Acan were upregulated by ascorbic acid in costal chondrocytes. Although the addition of Asc-2P led to an increase in COL10 expression according to qPCR and RNA-seq results, the immunofluorescence staining results of the two groups of TECs exhibited similar distribution and fluorescence intensity. In vivo experiments showed that both groups of TEC could adhere to the defect sites and kept hyaline cartilage morphology until 12 weeks. TEC treated with ascorbic acid showed superior cartilage regeneration as evidenced by significantly higher ICRS and O'Driscoll scores and stronger Safranin-O and collagen staining mimicking native cartilage when compared to other groups. In addition, the immunohistochemical staining results of Collgan X indicated that, after 12 weeks, the ascorbic acid-treated TEC did not exhibit further hypertrophy upon transplantation into the defect site, but maintained an expression profile similar to untreated TECs, while slightly higher than the sham-operated group.

Conclusion

These results suggest that CC-derived scaffold-free TEC presents a promising method for articular cartilage regeneration. Ascorbic acid treatment enhances outcomes by promoting cartilage matrix production. This study provides valuable insights and potential advancements in the field of cartilage tissue engineering.

The translational potential of this article

Cartilage tissue engineering is an area of research with immense clinical potential. The approach presented in this article offers a cost-effective and straightforward solution, which can minimize the complexity of cell culture and scaffold fabrication. This simplification could offer several translational advantages, such as ease of use, rapid scalability, lower costs, and the potential for patient-specific clinical translation. The use of costal chondrocytes, which are easily obtainable, and the scaffold-free approach, which does not require specialized equipment or membranes, could be particularly advantageous in clinical settings, allowing for in situ regeneration of cartilage.

Costal chondrocyte-derived pellet-type scaffold-free autologous chondrocyte implantation provided acceptable mid-term outcomes in osteochondral defects with up to 10-mm depth

PURPOSE

To evaluate clinical, radiographic, and magnetic resonance (MR) results of costal chondrocyte-derived pellet-type scaffold-free autologous chondrocyte implantation (CCP-ACI) in osteochondral defects (ODs) up to 10-mm depth during 5 years of follow-up.

METHODS

Ten patients with CCP-ACI performed in ODs with depth up to 10 mm were retrospectively analyzed. The minimum follow-up period was 5 years. The median age was 36.5 (range 20-55) years. The median size and the depth of the OD lesion were 4.25 cm2 (range 2-6) and 7.0 mm (6-9), respectively. Clinically, the International Knee Documentation Committee, Lysholm, and visual analog scale pain scores were evaluated. Radiographically, the hip‒knee‒ankle (HKA) angle and the Kellgren‒Lawrence (K‒L) grade were assessed. On MR imaging, the magnetic resonance observation of cartilage repair tissue (MOCART) 2.0 score and the defect depth were evaluated.

RESULTS

All average clinical scores improved significantly by 1, 2, and 5 years postoperatively. The average HKA angle and the proportion of K‒L grade did not change significantly within 5 years. The median total MOCART scores were 50 (range 45-65), 50 (35-90), 57.5 (40-90), and 65 (50-85) at 6 months, 1 year, 2 years, and 5 years postoperatively, respectively (p = 0.001), with significant improvement at 2 years compared to that at 6 months postoperatively. The signal intensity of the repair tissue and subchondral change significantly improved from 10 (range 10-10) to 12.5 (10-15) (p = 0.036), and from 10 (10-10) to 17.5 (0-20) (p = 0.017), respectively. Significant improvements were seen at 5 years postoperatively for the former and at 2 years postoperatively for the latter. The average depths on MR imaging were 6.7, 6.7, 6.8, 6.6, and 6.6 mm preoperatively and at 6 months, 1 year, 2 years, and 5 years postoperatively with no significant changes (n.s).

CONCLUSION

CCP-ACI provided acceptable mid-term outcomes in ODs up to 10-mm in depth without bone grafting despite of no scaffold. The procedure can be one of minimally invasive treatment options for ODs without scaffold-related problems.

LEVEL OF EVIDENCE

IV.

Costal Cartilage Graft Repair Osteochondral Defect in a Mouse Model

OBJECTIVE

Osteochondral defects develop into osteoarthritis without intervention. Costal cartilage can be utilized as an alternative source for repairing osteochondral defect. Our previous clinical study has shown the successful osteochondral repair by costal cartilage graft with integration into host bone bed. In this study, we investigate how cartilaginous graft adapt to osteochondral environment and the mechanism of bone-cartilage interface formation.

DESIGN

Costal cartilage grafting was performed in C57BL/6J mice and full-thickness osteochondral defect was made as control. 3D optical profiles and micro-CT were applied to evaluate the reconstruction of articular cartilage surface and subchondral bone as well as gait analysis to evaluate articular function. Histological staining was performed at 2, 4, and 8 weeks after surgery. Moreover, costal cartilage from transgenic mice with fluorescent markers were transplanted into wild-type mice to observe the in vivo changes of costal chondrocytes.

RESULTS

At 8 weeks after surgery, 3D optical profiles and micro-CT showed that in the graft group, the articular surface and subchondral bone were well preserved. Gait analysis and International Cartilage Repair Society (ICRS) score evaluation showed a good recovery of joint function and histological repair in the graft group. Safranin O staining showed the gradual integration of graft and host tissue. Costal cartilage from transgenic mice with fluorescent markers showed that donor-derived costal chondrocytes turned into osteocytes in the subchondral area of host femur.

CONCLUSION

Costal cartilage grafting shows both functional and histological repair of osteochondral defect in mice. Graft-derived costal chondrocytes differentiate into osteocytes and contribute to endochondral ossification.

Cytomodulin-10 modified GelMA hydrogel with kartogenin for in-situ osteochondral regeneration

The incidence of osteochondral defect is increasing year by year, but there is still no widely accepted method for repairing the defect. Hydrogels loaded with bioactive molecules have provided promising alternatives for in-situ osteochondral regeneration. Kartogenin (KGN) is an effective and steady small molecule with the function of cartilage regeneration and protection which can be further boosted by TGF-β. However, the high cost, instability, and immunogenicity of TGF-β would limit its combined effect with KGN in clinical application. In this study, a composite hydrogel CM-KGN@GelMA, which contained TGF-β1 analog short peptide cytomodulin-10 (CM-10) and KGN, was fabricated. The results indicated that CM-10 modified on GelMA hydrogels exerted an equivalent role in enhancing chondrogenesis as TGF-β1, and this effect was also boosted when combined with KGN. Moreover, it was revealed that CM-10 and KGN had a synergistic effect on promoting the chondrogenesis of BMSCs by up-regulating the expression of RUNX1 and SOX9 at both mRNA and protein levels in vitro. Finally, the composite hydrogel exhibited a satisfactory osteochondral defect repair effect in vivo, showing similar structures close to the native tissue. Taken together, this study has revealed that CM-10 may serve as an alternative for TGF-β1 and can collaborate with KGN to accelerate chondrogenesis, which suggests that the fabricated CM-KGN@GelMA composite hydrogel can be acted as a potential scaffold for osteochondral defect regeneration. STATEMENT OF SIGNIFICANCE: Kartogenin and TGF-β have shown great value in promoting osteochondral defect regeneration, and their combined application can enhance the effect and show great potential for clinical application. Herein, a functional CM-KGN@GelMA hydrogel was fabricated, which was composed of TGF-β1 mimicking peptide CM-10 and KGN. CM-10 in hydrogel retained an activity like TGF-β1 to facilitate BMSC chondrogenesis and exhibited boosting chondrogenesis by up-regulating RUNX1 and SOX9 when being co-applied with KGN. In vivo, the hydrogel promoted cartilage regeneration and subchondral bone reconstruction, showing similar structures as the native tissue, which might be vital in recovering the bio-function of cartilage. Thus, this study developed an effective scaffold and provided a promising way for osteochondral defect repair.

Zonally Stratified Decalcified Bone Scaffold with Different Stiffness Modified by Fibrinogen for Osteochondral Regeneration of Knee Joint Defect

Articular cartilage is generally known to be a complex tissue with multiple layers. Each layer has different composition, structure, and mechanical properties, making regeneration after knee joint defects a troubling clinical problem. A novel integrated stratified decalcified bone matrix (SDBM) scaffold with different stiffness to mimic the mechanical properties of articular cartilage is presented herein. This SDBM scaffold was modified using fibrinogen (Fg) (Fg + SDBM) to enhance its vascularization ability and improve its repair efficiency for osteochondral defects of knee joints. A Fg + SDBM scaffold with different elastic modulus in each layer (high-stiffness DBM (HDBM) layer, 174.208 ± 44.330 MPa (Fg + HDBM); medium-stiffness DBM (MDBM) layer, 21.214 ± 6.922 MPa (Fg + MDBM); and low-stiffness DBM (LDBM) layer, 0.678 ± 0.269 MPa (Fg + LDBM)) was constructed by controlling the stratified decalcification time with layered embedding paraffin (0, 3, and 5 days). The low- and medium-stiffness layers of the Fg + SDBM scaffold remarkably promoted the cartilage differentiation of bone marrow mesenchymal stem cells in vitro. Subcutaneous transplantation and rabbit knee joint osteochondral defect repair experiments revealed that the low- and medium-stiffness layers of the Fg + SDBM scaffold exhibited wonderful cartilage capacity, whereas the high-stiffness layer of Fg + SDBM scaffold exhibited good osteogenesis ability. Furthermore, this scaffold could promote blood vessel formation in subchondral bone area. This study presents a feasible strategy for osteochondral regeneration of defective knee joints, which is of great clinical value for tissue repair.

Strategies to Convert Cells into Hyaline Cartilage: Magic Spells for Adult Stem Cells

Damaged hyaline cartilage gradually decreases joint function and growing pain significantly reduces the quality of a patient’s life. The clinically approved procedure of autologous chondrocyte implantation (ACI) for treating knee cartilage lesions has several limits, including the absence of healthy articular cartilage tissues for cell isolation and difficulties related to the chondrocyte expansion in vitro. Today, various ACI modifications are being developed using autologous chondrocytes from alternative sources, such as the auricles, nose and ribs. Adult stem cells from different tissues are also of great interest due to their less traumatic material extraction and their innate abilities of active proliferation and chondrogenic differentiation. According to the different adult stem cell types and their origin, various strategies have been proposed for stem cell expansion and initiation of their chondrogenic differentiation. The current review presents the diversity in developing applied techniques based on autologous adult stem cell differentiation to hyaline cartilage tissue and targeted to articular cartilage damage therapy.

Co-culture pellet of human Wharton's jelly mesenchymal stem cells and rat costal chondrocytes as a candidate for articular cartilage regeneration: in vitro and in vivo study

BACKGROUND

Seeding cells are key factors in cell-based cartilage tissue regeneration. Monoculture of either chondrocyte or mesenchymal stem cells has several limitations. In recent years, co-culture strategies have provided potential solutions. In this study, directly co-cultured rat costal chondrocytes (CCs) and human Wharton's jelly mesenchymal stem (hWJMSCs) cells were evaluated as a candidate to regenerate articular cartilage.

METHODS

Rat CCs are directly co-cultured with hWJMSCs in a pellet model at different ratios (3:1, 1:1, 1:3) for 21 days. The monoculture pellets were used as controls. RT-qPCR, biochemical assays, histological staining and evaluations were performed to analyze the chondrogenic differentiation of each group. The 1:1 ratio co-culture pellet group together with monoculture controls were implanted into the osteochondral defects made on the femoral grooves of the rats for 4, 8, 12 weeks. Then, macroscopic and histological evaluations were performed.

RESULTS

Compared to rat CCs pellet group, 3:1 and 1:1 ratio group demonstrated similar extracellular matrix production but less hypertrophy intendency. Immunochemistry staining found the consistent results. RT-PCR analysis indicated that chondrogenesis was promoted in co-cultured rat CCs, while expressions of hypertrophic genes were inhibited. However, hWJMSCs showed only slightly improved in chondrogenesis but not significantly different in hypertrophic expressions. In vivo experiments showed that all the pellets filled the defects but co-culture pellets demonstrated reduced hypertrophy, better surrounding cartilage integration and appropriate subchondral bone remodeling.

CONCLUSION

Co-culture of rat CCs and hWJMSCs demonstrated stable chondrogenic phenotype and decreased hypertrophic intendency in both vitro and vivo. These results suggest this co-culture combination as a promising candidate in articular cartilage regeneration.

Functionalized Hydrogels for Cartilage Repair: The Value of Secretome-Instructive Signaling

Cartilage repair has been a challenge in the medical field for many years. Although treatments that alleviate pain and injury are available, none can effectively regenerate the cartilage. Currently, regenerative medicine and tissue engineering are among the developed strategies to treat cartilage injury. The use of stem cells, associated or not with scaffolds, has shown potential in cartilage regeneration. However, it is currently known that the effect of stem cells occurs mainly through the secretion of paracrine factors that act on local cells. In this review, we will address the use of the secretome—a set of bioactive factors (soluble factors and extracellular vesicles) secreted by the cells—of mesenchymal stem cells as a treatment for cartilage regeneration. We will also discuss methodologies for priming the secretome to enhance the chondroregenerative potential. In addition, considering the difficulty of delivering therapies to the injured cartilage site, we will address works that use hydrogels functionalized with growth factors and secretome components. We aim to show that secretome-functionalized hydrogels can be an exciting approach to cell-free cartilage repair therapy.