The Use of Particulated Juvenile Allograft Cartilage for the Repair of Porcine Articular Cartilage Defects

Collagen 1 gel may improve the regenerative capacity of minced adult and preosteoarthritic cartilage

PURPOSE

Minced cartilage implantation (MCI) is an evolving technique for the treatment of osteochondral lesions. It was hypothesised that mincing of cartilage may affect chondrocyte viability and phenotype and that embedding in collagen 1 gel results in an improved outcome. The objective of this study was to evaluate the impact of cartilage mincing and whether collagen 1 gel mediates beneficial effects on the chondrocyte phenotype and viability.

METHODS

Human cartilage samples from 11 patients undergoing total knee arthroplasty were collected and minced according to the MCI protocol. Minced cartilage was cultured for 1 week with and without embedding in collagen 1 gel and was compared with unminced cartilage flakes as control. Quantitative reverse transcription-PCR and immunohistochemical staining for the chondrocyte marker genes SOX9, COL2, ACAN, COL10 and MMP13 were used to examine the chondrocyte phenotype. Cell death was assessed by the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay.

RESULTS

Increased chondrocyte cell death of cultured cartilage after mincing was observed. Chondrocytes from minced cartilage exhibited significantly decreased expression and protein levels of homeostatic and hypertrophic chondrocyte markers. Embedding in collagen 1 gel showed no positive effect on viability. However, remarkable is the increased expression of ACAN and the preserved protein level of SOX9 in the collagen 1-embedded minced cartilage.

CONCLUSIONS

This study shows that the mincing of cartilage leads to increased chondrocyte death and decreased expression of chondrocyte phenotypic marker genes after 7 days. The use of collagen 1 gel may improve the stability of the phenotype, which needs to be further elucidated.

LEVEL OF EVIDENCE

Level III (therapeutic).

Regeneration of joint surface defects by transplantation of allogeneic cartilage: application of iPS cell-derived cartilage and immunogenicity

BACKGROUND

Because of its poor intrinsic repair capacity, articular cartilage seldom heals when damaged.

MAIN BODY

Regenerative treatment is expected for the treatment of articular cartilage damage, and allogeneic chondrocytes or cartilage have an advantage over autologous chondrocytes, which are limited in number. However, the presence or absence of an immune response has not been analyzed and remains controversial. Allogeneic-induced pluripotent stem cell (iPSC)-derived cartilage, a new resource for cartilage regeneration, reportedly survived and integrated with native cartilage after transplantation into chondral defects in knee joints without immune rejection in a recent primate model. Here, we review and discuss the immunogenicity of chondrocytes and the efficacy of allogeneic cartilage transplantation, including iPSC-derived cartilage.

SHORT CONCLUSION

Allogeneic iPSC-derived cartilage transplantation, a new therapeutic option, could be a good indication for chondral defects, and the development of translational medical technology for articular cartilage damage is expected.

Dual-tissue transplantation versus osteochondral autograft transplantation in the treatment of osteochondral defects: a porcine model study

BACKGROUND

Osteochondral injury is a common sports injury, and hyaline cartilage does not regenerate spontaneously when injured. However, there is currently no gold standard for treating osteochondral defects. Osteochondral autograft transplantation (OAT) is widely used in clinical practice and is best used to treat small osteochondral lesions in the knee that are < 2 cm² in size. Autologous dual-tissue transplantation (ADTT) is a promising method with wider indications for osteochondral injuries; however, ADTT has not been evaluated in many studies. This study aimed to compare the radiographic and histological results of ADTT and OAT for treating osteochondral defects in a porcine model.

METHODS

Osteochondral defects were made in the bilateral medial condyles of the knees of 12 Dian-nan small-ear pigs. The 24 knees were divided into the ADTT group (n = 8), OAT group (n = 8), and empty control group (n = 8). At 2 and 4 months postoperatively, the knees underwent gross evaluation based on the International Cartilage Repair Society (ICRS) score, radiographic assessment based on CT findings and the magnetic resonance observation of cartilage repair tissue (MOCART) score, and histological evaluation based on the O'Driscoll histological score of the repair tissue.

RESULTS

At 2 months postoperatively, the ICRS score, CT evaluation, MOCART score, and O'Driscoll histological score were significantly better in the OAT group than the ADTT group (all P < 0.05). At 4 months postoperatively, the ICRS score, CT evaluation, MOCART score, and O'Driscoll histological score tended to be better in the OAT group than the ADTT group, but these differences did not reach statistical significance (all P > 0.05).

CONCLUSIONS

In a porcine model, ADTT and OAT are both effective treatments for osteochondral defects in weight bearing areas. ADTT may be useful as an alternative procedure to OAT for treating osteochondral defects.

Engraftment of allogeneic iPS cell-derived cartilage organoid in a primate model of articular cartilage defect

Induced pluripotent stem cells (iPSCs) are a promising resource for allogeneic cartilage transplantation to treat articular cartilage defects that do not heal spontaneously and often progress to debilitating conditions, such as osteoarthritis. However, to the best of our knowledge, allogeneic cartilage transplantation into primate models has never been assessed. Here, we show that allogeneic iPSC-derived cartilage organoids survive and integrate as well as are remodeled as articular cartilage in a primate model of chondral defects in the knee joints. Histological analysis revealed that allogeneic iPSC-derived cartilage organoids in chondral defects elicited no immune reaction and directly contributed to tissue repair for at least four months. iPSC-derived cartilage organoids integrated with the host native articular cartilage and prevented degeneration of the surrounding cartilage. Single-cell RNA-sequence analysis indicated that iPSC-derived cartilage organoids differentiated after transplantation, acquiring expression of PRG4 crucial for joint lubrication. Pathway analysis suggested the involvement of SIK3 inactivation. Our study outcomes suggest that allogeneic transplantation of iPSC-derived cartilage organoids may be clinically applicable for the treatment of patients with chondral defects of the articular cartilage; however further assessment of functional recovery long term after load bearing injuries is required.

Vitrified Particulated Articular Cartilage for Joint Resurfacing: A Swine Model

BACKGROUND

The use of particulated articular cartilage for repairing cartilage defects has been well established, but its use is currently limited by the availability and short shelf life of donor cartilage. Vitrification is an ice-free cryopreservation technology at ultralow temperatures for tissue banking. An optimized vitrification protocol has been developed for particulated articular cartilage; however, the equivalency of the long-term clinical efficacy of vitrified particulated articular cartilage compared with fresh articular cartilage has not yet been determined.

HYPOTHESIS

The repair effect of vitrified particulated cartilage from pigs would be equivalent to or better than that of fresh particulated cartilage stored at 4°C for 21 days.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 19 pigs were randomly divided into 3 experimental groups: fresh particulated cartilage group (n = 8), vitrified particulated cartilage group (n = 8), and negative control group (no particulated cartilage in the defect; n = 3). An additional pig was used as the initial cartilage donor for the first set of surgical procedures. Pigs were euthanized after 6 months to obtain femoral condyles, and the contralateral condyle was used as the positive (no defect) control. Samples were evaluated for gross morphology using the Outerbridge and Osteoarthritis Research Society International (OARSI) scoring systems, histology (safranin O, collagen type I/II, DAPI), and chondrocyte viability using live-dead membrane integrity staining.

RESULTS

There were no infections after surgery, and all 19 pigs were followed for the duration of the study. The OARSI grades for the fresh and vitrified particulated cartilage groups were 2.44 ± 1.35 and 2.00 ± 0.80, respectively, while the negative control group was graded significantly higher at 4.83 ± 0.29. Analysis of histological and fluorescent staining demonstrated that the fresh and vitrified particulated cartilage groups had equivalent regeneration within cartilage defects, with similar cell viability and densities and expression of proteoglycans and collagen type I/II.

CONCLUSION

The implantation of fresh or vitrified particulated cartilage resulted in the equivalent repair of focal cartilage defects when evaluated at 6 months after surgery.

CLINICAL RELEVANCE

The vitrification of particulated cartilage is a viable option for long-term storage for cartilage tissue banking and could greatly increase the availability of donor tissue for transplantation.

Engineering of MSC-Derived Exosomes: A Promising Cell-Free Therapy for Osteoarthritis

Osteoarthritis (OA) is characterized by progressive cartilage degeneration with increasing prevalence and unsatisfactory treatment efficacy. Exosomes derived from mesenchymal stem cells play an important role in alleviating OA by promoting cartilage regeneration, inhibiting synovial inflammation and mediating subchondral bone remodeling without the risk of immune rejection and tumorigenesis. However, low yield, weak activity, inefficient targeting ability and unpredictable side effects of natural exosomes have limited their clinical application. At present, various approaches have been applied in exosome engineering to regulate their production and function, such as pretreatment of parental cells, drug loading, genetic engineering and surface modification. Biomaterials have also been proved to facilitate efficient delivery of exosomes and enhance treatment effectiveness. Here, we summarize the current understanding of the biogenesis, isolation and characterization of natural exosomes, and focus on the large-scale production and preparation of engineered exosomes, as well as their therapeutic potential in OA, thus providing novel insights into exploring advanced MSC-derived exosome-based cell-free therapy for the treatment of OA.

Advanced Hydrogels With Nanoparticle Inclusion for Cartilage Tissue Engineering

Cartilage dysfunctions caused by congenital disease, trauma and osteoarthritis are still a serious threat to joint activity and quality of life, potentially leading to disability. The relatively well-established tissue engineering technology based on hydrogel is a promising strategy for cartilage defect repairing. However, several unmet challenges remain to be resolved before its wide application and clinical translation, such as weak mechanical property and compromised bioactivity. The development of nanomedicine has brought a new dawn to cartilage tissue engineering, and composite hydrogel containing nanoparticles can substantially mimic natural cartilage components with good histocompatibility, demonstrating unique biological effects. In this review, we summarize the different advanced nanoparticle hydrogels currently adopted in cartilage tissue engineering. In addition, we also discuss the various application scenarios including injection and fabrication strategies of nanocomposite hydrogel in the field of cartilage repair. Finally, the future application prospects and challenges of nanocomposite hydrogel are also highlighted.

Patellofemoral joint cartilage restoration with particulated juvenile allograft in patients under 21 years old

BACKGROUND

Patellofemoral joint cartilage defects are difficult to treat due to their unique thickness and topography.

PURPOSE

To report the postoperative outcomes of patients age 21 and younger treated with particulated juvenile allograft cartilage (PJAC) for full-thickness cartilaginous defects of the patellofemoral joint. The primary aim was to report surgical outcomes and complication rates, as well as return to sport activity. A secondary aim was to provide objective scores of defect restoration by magnetic resonance imaging (MRI) assessment.

METHODS

A retrospective review of all PJAC cases conducted between 2012 and 2019 at a single tertiary care urban musculoskeletal institution was conducted. Patients 21 years old or younger with minimum clinical follow up of 1 year and postoperative MRI at a minimum of 6 months were included. Cartilage restoration by MRI was independently assessed using the International Cartilage Repair Society's (ICRS) standardized system.

RESULTS

Thirty four patients, 36 knees, were included, with mean age 16.1 ± 3.1 years old. Return to sport rate among patients who participated in a sport preoperatively was 100%. On independent MRI assessment, two thirds of defects achieved an overall grade of normal or nearly normal, while 28 patients (78%) had majority defect fill. Primary graft failure occurred in two cases and one patient experienced a surgical complication.

CONCLUSION

Restoration of patellofemoral chondral defects in young patients with particulated juvenile allograft results in satisfactory short-term outcomes and postoperative MRI appearance, along with high rates of return to sport and low rate of complications and graft failure. What is known about the subject: Patellofemoral joint cartilage defects are difficult to treat due to their unique thickness and topography. Several cartilage restoration techniques are available, but these rarely achieve the same mechanical properties as native hyaline cartilage. PJAC is a cell-based technique that has demonstrated promise since its introduction in 2007.

WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE

This series of patients adds the largest single cohort of pediatric and adolescent patients who receive PJAC for defects of the patellofemoral joint. Surgeons treating patients in this age group should be aware of every technique, and their respective outcomes.

Human acellular amniotic membrane scaffolds encapsulating juvenile cartilage fragments accelerate the repair of rabbit osteochondral defects

Aims

The purpose of this study was to explore a simple and effective method of preparing human acellular amniotic membrane (HAAM) scaffolds, and explore the effect of HAAM scaffolds with juvenile cartilage fragments (JCFs) on osteochondral defects.

Methods

HAAM scaffolds were constructed via trypsinization from fresh human amniotic membrane (HAM). The characteristics of the HAAM scaffolds were evaluated by haematoxylin and eosin (H&E) staining, picrosirius red staining, type II collagen immunostaining, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Human amniotic mesenchymal stem cells (hAMSCs) were isolated, and stemness was verified by multilineage differentiation. Then, third-generation (P3) hAMSCs were seeded on the HAAM scaffolds, and phalloidin staining and SEM were used to detect the growth of hAMSCs on the HAAM scaffolds. Osteochondral defects (diameter: 3.5 mm; depth: 3 mm) were created in the right patellar grooves of 20 New Zealand White rabbits. The rabbits were randomly divided into four groups: the control group (n = 5), the HAAM scaffolds group (n = 5), the JCFs group (n = 5), and the HAAM + JCFs group (n = 5). Macroscopic and histological assessments of the regenerated tissue were evaluated to validate the treatment results at 12 weeks.

Results

In vitro, the HAAM scaffolds had a network structure and possessed abundant collagen. The HAAM scaffolds had good cytocompatibility, and hAMSCs grew well on the HAAM scaffolds. In vivo, the macroscopic scores of the HAAM + JCFs group were significantly higher than those of the other groups. In addition, histological assessments demonstrated that large amounts of hyaline-like cartilage formed in the osteochondral defects in the HAAM + JCFs group. Integration with surrounding normal cartilage and regeneration of subchondral bone in the HAAM + JCFs group were better than those in the other groups.

Conclusion

HAAM scaffolds combined with JCFs promote the regenerative repair of osteochondral defects.

Cite this article: Bone Joint Res 2022;11(6):349–361.

Hydrogel composed of type II collagen, chondroitin sulfate and hyaluronic acid for cartilage tissue engineering

BACKGROUND

Cartilage tissue engineering is a promising way to repair cartilage defects. Different materials have been applied in the preparation of cartilage hydrogels, but all with various disadvantages.

OBJECTIVE

The aim of this study was to prepare cartilage hydrogel using type II collagen, chondroitin sulfate and hyaluronic acid, to explore their gelation effect and compressive strength, and to analyze the feasibility of their application in cartilage tissue engineering.

METHODS

Type II collagen (Col II), hyaluronic acid (HA) and chondroitin sulfate (CS) were mixed in a certain proportion to prepare gel scaffolds; changes in chemical groups were detected by Fourier transform infrared. After the hydrogel was prepared, its compressive strength was measured. Umbilical cord stem cells were co-cultured with hydrogel scaffolds to observe its cytocompatibility and analyze whether stem cells had cellular activity during co-culture; histological staining was applied to observe the hydrogel loaded with stem cells.

RESULTS

Cartilage hydrogels were successfully prepared with good compressive strength, and Fourier transform infrared analysis showed that Schiff base reaction occurred during the preparation process and tight chemical cross-linking was formed. The results of umbilical cord stem cell co-culture showed that the hydrogel had good cytocompatibility and the stem cells had good activity in the hydrogel.

CONCLUSIONS

Cartilage hydrogels with stable structures were successfully prepared and had good compressive strength. Hydrogel scaffold could provide a suitable living environment for umbilical cord stem cells, so that they maintain normal cell morphology and activity, and has a good application potential in cartilage tissue engineering.

Particulated Juvenile Articular Cartilage and Matrix-Induced Autologous Chondrocyte Implantation Are Cost-Effective for Patellar Chondral Lesions

PURPOSE

To compare the cost-effectiveness of nonoperative management, particulated juvenile allograft cartilage (PJAC), and matrix-induced autologous chondrocyte implantation (MACI) in the management of patellar chondral lesions.

METHODS

A Markov model was used to evaluate the cost-effectiveness of three strategies for symptomatic patellar chondral lesions: 1) nonoperative management, 2) PJAC, and 3) MACI. Model inputs (transition probabilities, utilities, and costs) were derived from literature review and an institutional cohort of 67 patients treated with PJAC for patellar chondral defects (mean age 26 years, mean lesion size 2.7 cm²). Societal and payer perspectives over a 15-year time horizon were evaluated. The principal outcome measure was the incremental cost-effectiveness ratio (ICER) using a $100,000/quality-adjusted life year (QALY) willingness-to-pay threshold. Sensitivity analyses were performed to assess the robustness of the model and the relative effects of variable estimates on base case conclusions.

RESULTS

From a societal perspective, nonoperative management, PJAC, and MACI cost $4,140, $52,683, and $83,073 and were associated with 5.28, 7.22, and 6.92 QALYs gained, respectively. PJAC and MACI were cost-effective relative to nonoperative management (ICERs $25,010/QALY and $48,344/QALY, respectively). PJAC dominated MACI in the base case analysis by being cheaper and more effective, but this was sensitive to the estimated effectiveness of both strategies. PJAC remained cost-effective if PJAC and MACI were considered equally effective.

CONCLUSIONS

In the management of symptomatic patellar cartilage defects, PJAC and MACI were both cost-effective compared to nonoperative management. Because of the need for one surgery instead of two, and less costly graft material, PJAC was cheaper than MACI. Consequently, when PJAC and MACI were considered equally effective, PJAC was more cost-effective than MACI. Sensitivity analyses accounting for the lack of robust long-term data for PJAC or MACI demonstrated that the cost-effectiveness of PJAC versus MACI depended heavily on the relative probabilities of yielding similar clinical results.

LEVEL OF EVIDENCE

III, economic and decision analysis.

Insights into the implementation of Fibronectin 1 in the cartilage tissue engineering

Recently, cartilage tissue engineering has become a cornerstone to treat cartilage degeneration and osteoarthritis (OA). Fibronectin1 (FN1) is described as multiple functional glycoproteins that play an essential role in chondrogenic and osteogenic differentiation. Few studies reported the potential of FN1 to enhance tissue engineering and reduce the death of chondrocytes in OA. Further, FN1 possesses multiple binding domains including collagen, integrin, and heparin that can interact with heparan sulfate proteoglycans at the surface of chondrocyte leading to promote cell signaling and differentiation. Recent studies suggested that FN1 can promote chondrocyte differentiation by upregulating TGF-β/PI3K/Akt pathways. Further, FN1 can inhibit the apoptosis of chondrocytes by preventing the release of metalloproteinases through lowering the expression of p-PI3K/PI3K and p-AKT/AKT pathways. However, the use of FN1 in cartilage repair studies using animal models or clinical trials was rarely reported. Therefore, this article provides new insights into the importance of FN1 in cartilage tissue engineering to encourage more studies concerning FN1 in cartilage repair studies. Further, we provided new suggestions for advanced applications of FN1 to treat OA and cartilage degeneration.

hAMSC Sheet Promotes Repair of Rabbit Osteochondral Defects

Osteochondral lesion is clinically common disease, which has been recognized as one of the contributing factors of significant morbidity. Although current treatments have achieved good outcomes, some undesirable complications and failures are not uncommon. Cell sheet technology (CST), an innovative technology to harvest seed cells and preserve abundant ECM, has been widely used in various tissue regeneration. For osteochondral lesion, many studies focus on using CST to repair osteochondral lesion and have achieved good outcomes. In the previous study, we have demonstrated that hAMSC sheet had a positive effect on osteochondral lesion. Therefore, this study is aimed at comparing the effect of noninduced hAMSC sheet with chondrogenically induced hAMSC sheet on osteochondral lesion and cartilage regeneration.

[Effect of silk fibroin microcarrier loaded with clematis total saponins and chondrocytes on promoting rabbit knee articular cartilage defects repair]

Objective

To prepare the silk fibroin microcarrier loaded with clematis total saponins (CTS) (CTS-silk fibroin microcarrier), and to investigate the effect of microcarrier combined with chondrocytes on promoting rabbit knee articular cartilage defects repair.

Methods

CTS-silk fibroin microcarrier was prepared by high voltage electrostatic combined with freeze drying method using the mixture of 5% silk fibroin solution, 10 mg/mL CTS solution, and glycerin. The samples were characterized by scanning electron microscope and the cumulative release amount of CTS was detected. Meanwhile, unloaded silk fibroin microcarrier was also prepared. Chondrocytes were isolated from knee cartilage of 4-week-old New Zealand rabbits and cultured. The 3rd generation of chondrocytes were co-cultured with the two microcarriers respectively for 7 days in microgravity environment. During this period, the adhesion of chondrocytes to microcarriers was observed by inverted phase contrast microscope and scanning electron microscope, and the proliferation activity of cells was detected by cell counting kit 8 (CCK-8), and compared with normal cells. Thirty 3-month-old New Zealand rabbits were selected to make bilateral knee cartilage defects models and randomly divided into 3 groups ( n=20). Knee cartilage defects in group A were not treated, and in groups B and C were filled with the unloaded silk fibroin microcarrier-chondrocyte complexes and CTS-silk fibroin microcarrier-chondrocyte complexes, respectively. At 12 weeks after operation, the levels of matrix metalloproteinase 9 (MMP-9), MMP-13, and tissue inhibitor of MMP 1 (TIMP-1) in articular fluid were detected by ELISA. The cartilage defects were collected for gross observation and histological observation (HE staining and toluidine blue staining). Western blot was used to detect the expressions of collagen type Ⅱ and proteoglycan. The inflammatory of joint synovium was observed by histological staining and inducible nitric oxide synthase (iNOS) immunohistochemical staining.

Results

The CTS-silk fibroin microcarrier was spherical, with a diameter between 300 and 500 μm, a porous surface, and a porosity of 35.63%±3.51%. CTS could be released slowly in microcarrier for a long time. Under microgravity, the chondrocytes attached to the surface of the two microcarriers increased gradually with the extension of culture time, and the proliferation activity of chondrocytes at 24 hours after co-culture was significantly higher than that of normal chondrocytes ( P<0.05). There was no significant difference in proliferation activity of chondrocytes between the two microcarriers ( P>0.05). In vivo experiment in animals showed that the levels of MMP-9 and MMP-13 in group C were significantly lower than those in groups A and B ( P<0.05), and the level of TIMP-1 in group C was significantly higher ( P<0.05). Compared with group A, the cartilage defects in groups B and C were filled with repaired tissue, and the repaired surface of group C was more complete and better combined with the surrounding cartilage. Histological observation and Western blot analysis showed that the International Cartilage Repair Scoring (ICRS) and the relative expression levels of collagen type Ⅱ and proteoglycan in groups B and C were significantly better than those in group A, and group C was significantly better than group B ( P<0.05). The histological observation showed that the infiltration of synovial inflammatory cells and hyperplasia of small vessels significantly reduced in group C compared with groups A and B. iNOS immunohistochemical staining showed that the expression of iNOS in group C was significantly lower than that in groups A and B ( P<0.05).

Conclusion

CTS-silk fibroin microcarrier has good CTS sustained release effect and biocompatibility, and can promote the repair of rabbit cartilage defect by carrying chondrocyte proliferation in microgravity environment.

The transplantation of particulated juvenile allograft cartilage and synovium for the repair of meniscal defect in a lapine model

Background

Synovium has been confirmed to be the primary contributor to meniscal repair. Particulated Juvenile Allograft Cartilage (PJAC) has demonstrated promising clinical effect on repairing cartilage. The synergistic effect of synovium and PJAC transplant on meniscal fibrocartilaginous repair is unclear. We hypothesize that the transplantation of synovium and PJAC synergistically facilitates meniscal regeneration and the donor cells within graft tissues still survive in the regenerated tissue at the last follow up (16 weeks postoperatively).

Methods

The study included 24 mature female rabbits, which were randomly divided into experimental and control groups. A cylindrical full-thickness defect measuring 2.0 ​mm was prepared in the avascular portion of the anterior horn of medial meniscus in both knees. The synovium and PJAC transplant were harvested from juvenile male rabbits (2 months after birth). The experimental group received synovium and PJAC transplant encapsulated with fibrin gel. The control groups received synovium transplant encapsulated with fibrin gel, pure fibrin gel and nothing. The macroscopic, imageological and histological evaluations of repaired tissue were performed at 8 weeks and 16 weeks postoperatively. The in situ hybridization (ISH) of male-specific sex-determining region Y-linked (SRY) gene was performed to detect the transplanted cells.

Results

The regenerated tissue in experimental group showed superior structural integrity, superficial smoothness, and marginal integration compared to control groups at 8 weeks or 16 weeks postoperatively. More meniscus-like fibrochondrocytes filled the repaired tissue in the experimental group, and the matrix surrounding these cell clusters demonstrated strongly positive safranin O and type 2 collagen immunohistochemistry staining. By SRY gene ISH, the positive SRY signal of experimental group could be detected at 8 weeks (75.72%, median) and 16 weeks (48.69%, median). The expression of SOX9 in experimental group was the most robust, with median positive rates of 65.52% at 8 weeks and 67.55% at 16 weeks.

Conclusion

The transplantation of synovium and PJAC synergistically facilitates meniscal regeneration. The donor cells survive for at least 16 weeks in the recipient.

The translational potential of this article

This study highlighted the positive effect of PJAC and synovium transplant on meniscal repair. We also clarified the potential repair mechanisms reflected by the survival of donor cells and upregulated expression of meniscal fibrochondrocytes related genes. Thus, based on our study, further clinical experiments are needed to investigate synovium and PJAC transplant as a possible treatment to meniscal defects.

Cartilage Repair Using Clematis Triterpenoid Saponin Delivery Microcarrier, Cultured in a Microgravity Bioreactor Prior to Application in Rabbit Model

Cartilage tissue engineering provides a promising method for the repair of articular cartilage defects, requiring appropriate biological scaffolds and necessary growth factors to enhance the efficiency of cartilage regeneration. Here, a silk fibroin (SF) microcarrier and a clematis triterpenoid saponin delivery SF (CTS-SF) microcarrier were prepared by the high-voltage electrostatic differentiation and lyophilization method, and chondrocytes were carried under the simulated microgravity condition by a rotating cell culture system. SF and CTS-SF microspheres were relatively uniform in size and had a porous structure with good swelling and cytocompatibility. Further, CTS-SF microcarriers could sustainably release CTSs in the monitored 10 days. Compared with the monolayer culture, chondrocytes under the microgravity condition maintained a better chondrogenic phenotype and showed better proliferation ability after culture on microcarriers. Moreover, the sustained release of CTS from CTS-SF microcarriers upregulated transforming growth factor-β, Smad2, and Smad3 signals, contributing to promote chondrogenesis. Hence, the biophysical effects of microgravity and bioactivities of CTS-ST were used for chondrocyte expansion and phenotype maintenance in vitro. With prolonged expansion, SF- and CTS-SF-based microcarrier-cell composites were directly implanted in vivo to repair rabbit articular defects. Gross evaluations, histopathological examinations, and biochemical analysis indicated that SF- and CTS-SF-based composites exhibited cartilage-like tissue repair compared with the nontreated group. Further, CTS-SF-based composites displayed superior hyaline cartilage-like repair that integrated with the surrounding cartilage better and higher cartilage extracellular matrix content. In conclusion, these results provide an alternative preparation method for drug-delivered SF microcarrier and a culture method for maintaining the chondrogenic phenotype of seed cells based on the microgravity environment. CTS showed its bioactive function, and the application of CTS-SF microcarriers can help repair and regenerate cartilage defects.

Particulated Cartilage for Chondral and Osteochondral Repair: A Review

INTRODUCTION

Injuries to articular cartilage have a poor spontaneous repair potential and no gold standard treatment exist. Particulated cartilage, both auto- and allograft, is a promising new treatment method that circumvents the high cost of scaffold- and cell-based treatments.

MATERIALS AND METHODS

A comprehensive database search on particulated cartilage was performed.

RESULTS

Fourteen animal studies have found particulated cartilage to be an effective treatment for cartilage injuries. Many studies suggest that juvenile cartilage has increased regenerative potential compared to adult cartilage. Sixteen clinical studies on 4 different treatment methods have been published. (1) CAIS, particulated autologous cartilage in a scaffold, (2) Denovo NT, juvenile human allograft cartilage embedded in fibrin glue, (3) autologous cartilage chips-with and without concomitant bone grafting, and (4) augmented autologous cartilage chips.

CONCLUSION

Implantation of allogeneic and autologous particulated cartilage provides a low cost and effective treatment alternative to microfracture and autologous chondrocyte implantation. The methods are promising, but large randomized controlled studies are needed.

Arthroscopic Minced Cartilage Implantation for Chondral Lesions at the Talus: A Technical Note

In the past few years, autologous chondrocyte implantation has been shown to be the most suitable cartilage reconstructive technique with the best tissue quality. Although this method is part of the standard surgical repertoire in the knee joint, it has so far not been an established method in the ankle because there are no prospective randomized controlled studies to prove a significant advantage over alternative methods of cartilage repair. The methods most frequently used in this context (e.g., marrow stimulation techniques) can, however, at most generate hyaline-like and thus biomechanically inferior regenerates. Minced cartilage implantation, on the other hand, is a relatively simple and cost-effective 1-step procedure with promising biological potential and-at least in the knee joint-satisfactory clinical results. We present an arthroscopic surgical technique by which the surgeon can apply autologous chondrocytes in a 1-step procedure (AutoCart; Arthrex, Munich, Germany) to treat articular cartilage defects in the ankle joint.

Particulated Autologous Chondral-Platelet-Rich Plasma Matrix Implantation (PACI) for Treatment of Full-Thickness Cartilage Osteochondral Defects

Articular hyaline cartilage injuries can occur as a result of either traumatic of progressive degeneration. When the articular cartilage in a joint is damaged, it can cause joint pain and dysfunction, predisposing patients for the development of early-onset osteoarthritis. There are many restoration procedures available to treat these injuries, such as bone marrow-stimulation techniques, osteoarticular auto/allograft transplants, and autologous chondrocyte implantation. Each of these techniques has its own limitations, which led researchers to explore new regenerative and repair techniques to produce normal hyaline cartilage. The purpose of this Technical Note is to describe in detail the particulated autologous chondral-platelet-rich plasma matrix implantation (PACI) technique that could be used as a single-stage cartilage restoration procedure for treatment of full-thickness cartilage and osteochondral defects.

Proliferation ability of particulated juvenile allograft cartilage

Background

Particulated juvenile allograft cartilage (PJAC) has a good short-term clinical efficacy in repairing articular cartilage defects, but the proliferation ability of PJAC and the biological characteristics of transplanted cells after transplantation are still unclear.

Purpose

To study the cartilage proliferation ability of PJAC in repairing full-thickness cartilage defects and the reasons for proliferation to provide experimental evidence for its clinical application.

Study design

Controlled laboratory study.

Methods

Twenty Guizhou minipigs were randomly divided into the experimental group and control group. In all minipigs, an 8-mm cylindrical full-thickness cartilage defect was created in the femoral trochlea of one knee. The experimental group received PJAC transplantation from five juvenile donors of Guizhou minipigs (PJAC group; n = 10) and the control group received transplantation of autologous cartilage chips (ACC group; n = 10). Both groups were followed at 1 and 3 months after surgery, immunohistochemical evaluation of the tissue sections Ki-67 and Lin28 was conducted, the positive rate was calculated according to the staining, and the proliferation ability of PJAC was analyzed.

Results

All 20 Guizhou minipigs were followed, and there was no infection or incision healing disorder after surgery. By Ki-67 and Lin28 immunohistochemical tests, the positive rate of Ki-67 was 88.9 ± 0.2% in the PJAC group and 28.3 ± 3.6% in the ACC group at 1 month, and the difference was statistically significant (P < 0.05); the positive rate of Lin28 was 34.6 ± 3.3% in the PJAC group and 7.6 ± 1.4% in the ACC group at 1 month, and the difference was statistically significant (P < 0.05). At 3 months, the positive rates of Ki-67 in the PJAC group and ACC group were 53.6 ± 6.9% and 1.97 ± 0.3%, respectively (P < 0.05); the positive rates of Lin28 were 86.6 ± 3.3% and 1.4 ± 0.3%, respectively (P < 0.01).

Conclusion

A large animal model was established with Guizhou minipigs, and the expressions of Ki-67 protein and Lin28 protein detected by immunohistochemistry in the repaired transplanted tissue of the PJAC group were stronger than those of adult cartilage. The proliferation of PJAC within 3 months of transplantation was stronger than that of adult cartilage. The enhanced expression of Lin28 may be one of the mechanisms by which PJAC achieved stronger proliferation ability than adult cartilage. PJAC technology has shown good application prospects for repairing cartilage defects.

Endoscopic Treatment of Symptomatic Foot and Ankle Bone Cyst with 3D Printing Application

Objective

To study the efficacy of arthroscopy for treating symptomatic bone cysts of the foot and ankle through the follow-up of patients and to further explore the application value of 3D printing technology in this treatment.

Methods

Twenty-one patients with symptomatic bone cysts in the foot and ankle who underwent arthroscopic surgery in our Center from March 2010 to December 2018 were enrolled, including 11 in the experimental group and 10 in the control group. For the control group, C-arm fluoroscopy was used intraoperatively to confirm the positioning of the cysts; for the experimental group, a 3D model of the lesion tissue and the 3D-printed individualized guides were prepared to assist the positioning of the cysts. Debridement of the lesion tissues was conducted under an arthroscope. Regular follow-ups were conducted. The time of establishing arthroscopic approaches and the times of intraoperative fluoroscopy between the two groups were compared. Significance was determined as P < 0.05.

Results

The postoperative pathology of the patients confirmed the diagnosis. No significant perioperative complications were observed in either group, and no recurrence of bone cysts was seen at the last follow-up. The VAS scores and AOFAS scores of the two groups at the last follow-up were significantly improved compared with the preoperative data, but there was no statistical difference between the two groups. All surgeries were performed by the same senior surgeon. The time taken to establish the arthroscopic approaches between the two groups was statistically significant (P < 0.001), and the times of intraoperative fluoroscopy required to establish the approach were also statistically significant (P < 0.001). The intraoperative bleeding between the two groups was statistically significant (P < 0.01). There was 1 case in each group whose postoperative CT showed insufficient bone grafting, but no increase in cavity volume was observed during the follow-up.

Conclusion

With the assistance of the 3D printing technology for treating symptomatic bone cysts of the ankle and foot, the surgeon can design the operation preoperatively and perform the rehearsal, which would make it easier to establish the arthroscopic approach, better understand the anatomy, and make the operation smoother. This trial is registered with http://www.clinicaltrials.govNCT03152916.

FGF2: a key regulator augmenting tendon-to-bone healing and cartilage repair

Ligament/tendon and cartilage injuries are clinically common diseases that perplex most clinicians. Because of the lack of blood vessels and nerves, their self-repairing abilities are rather poor. Therefore, surgeries are necessary and also widely used to treat ligament/tendon or cartilage injuries. However, after surgery, there are still many problems that affect healing. In recent years, it has been found that exogenous FGF2 plays an important role in the repair of ligament/tendon and cartilage injuries and exerts a synergistic effect with endogenous FGF2. Therefore, FGF2 can be used as a new type of biomolecule to accelerate tendon-to-bone healing and cartilage repair after injury.

Donor Cell Fate in Particulated Juvenile Allograft Cartilage for the Repair of Articular Cartilage Defects

BACKGROUND

Particulated juvenile allograft cartilage (PJAC) has demonstrated good clinical efficacy in repairing articular cartilage defects, but the related repair mechanism after transplant and the biological characteristics of the transplanted cells are still unclear.

PURPOSE

To study the efficacy of PJAC in repairing full-thickness cartilage defects and the specific fate of donor cells to provide experimental evidence for its clinical application.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty female Guizhou minipigs were randomly divided into an experimental group and a control group. An 8-mm cylindrical full-thickness cartilage defect was created in the femoral trochlea of 1 knee in all minipigs. The experimental group received transplant of PJAC from 5 male juvenile Guizhou minipigs (PJAC group; n = 10) and the control group received autologous cartilage chips (ACC group; n = 10). Follow-up assessments were conducted at 1 month and 3 months to track the transplanted cells by the male-specific sex-determining region Y-linked (SRY) gene; tissue sections were hybridized in situ, and O'Driscoll histological scoring was performed according to hematoxylin and eosin staining, safranin O and fast green staining, and toluidine blue O staining, as well as immunohistochemical evaluation of aggrecan and Sry-type HMG-box 9 (SOX9).

RESULTS

All 20 Guizhou minipigs were followed; no infection or incision healing disorder occurred after the operation. By SRY in situ hybridization, the SRY signal of the transplanted cells was positive in the repaired tissue of the defect, and the SRY positive signal could still be detected in repaired tissue at 3 months postoperatively. The average number of positive cells was 68.6 ± 11.91 at 1 month and 32.6 ± 3.03 at 3 months (confocal microscope: ×400), and the difference was statistically significant. The O'Driscoll histological scores were 14 ± 0.71 in the ACC group and 9.8 ± 0.84 in the PJAC group at 1 month, and 18 ± 1.20 in the ACC group and 17.4 ± 1.14 in the PJAC group at 3 months. The scores were statistically significant between the ACC group and PJAC group at 1 month. The positive rates of SOX9 in the PJAC and ACC groups at 1 month were 67.6% ± 3.78% and 63.4% ± 5.30%, respectively, and the difference was not statistically significant (P > .05). The positive rates of SOX9 in the PJAC and ACC groups at 3 months were 68.8% ± 2.69% and 17.1% ± 1.26%, respectively, and the difference was statistically significant (P < .05). The positive rates of aggrecan in the PJAC and ACC groups at 1 month were 40.5% ± 2.78% and 42.4% ± 0.54% respectively, and the difference was not statistically significant (P > .05). The positive rates of aggrecan in the PJAC and ACC groups at 3 months were 40.8% ± 1.50% and 30.1% ± 2.44%, respectively, and the difference was not statistically significant (P > .05).

CONCLUSION

An animal model was established with Guizhou minipigs, and the cartilage defect was repaired with PJAC from male minipigs. The SRY gene positive signal could be detected from the repaired tissue by in situ hybridization, indicating that the transplanted cells survived at least 3 months. The key genes of cartilage formation, SOX9 and aggrecan, were expressed at 1 month and 3 months, and SOX9 expression was stronger in the PJAC group than the ACC group at 3 months.

CLINICAL RELEVANCE

This study suggests that it is feasible to study the biological characteristics of transplanted cells in the cartilage region by the sex-determining gene.

Autologous Fractionated Adipose Tissue as a Natural Biomaterial and Novel One-Step Stem Cell Therapy for Repairing Articular Cartilage Defects

Articular cartilage damage remains a tough challenge for clinicians. Stem cells have emerged promising biologics in regenerative medicine. Previous research has widely demonstrated that adipose-derived mesenchymal stem cells (ADSCs) can promote cartilage repair due to their multipotency. However, enzymatic isolation and monolayer expansion of ADSCs decrease their differentiation potential and limit their clinical application. Here, a novel adipose tissue-derived product, extracellular matrix/stromal vascular fraction gel (ECM/SVF-gel), was obtained by simple mechanical shifting and centrifugation to separate the fat oil and concentrate the effective constituents. This study aimed to evaluate the therapeutic effect of this natural biomaterial on the repair of articular cartilage defects. Scanning electron microscopy showed that the fibrous structure in the ECM/SVF-gel was preserved. ADSCs sprouted from the ECM/SVF-gel were characterized by their ability of differentiation into chondrocytes, osteoblasts, and adipocytes. In a rabbit model, critical-sized cartilage defects (diameter, 4 mm; depth, 1.5 mm) were created and treated with microfracture (MF) or a combination of autologous ECM/SVF-gel injection. The knee joints were evaluated at 6 and 12 weeks through magnetic resonance imaging, macroscopic observation, histology, and immunohistochemistry. The International Cartilage Repair Society score and histological score were significantly higher in the ECM/SVF-gel group than those in the MF-treated group. The ECM/SVF-gel distinctly improved cartilage regeneration, integration with surrounding normal cartilage, and the expression of hyaline cartilage marker, type II collagen, in comparison with the MF treatment alone. Overall, the ready-to-use ECM/SVF-gel is a promising therapeutic strategy to facilitate articular cartilage regeneration. Moreover, due to the simple, time-sparing, cost-effective, enzyme-free, and minimally invasive preparation process, this gel provides a valuable alternative to stem cell-based therapy for clinical translation.