Particulated Cartilage for Chondral and Osteochondral Repair: A Review

Osteochondral Injuries of the Talus

Osteochondral lesions of the talus are a common sequelae of trauma and are often associated with ankle sprains and ankle fractures. Because the surface of the talus is composed primarily of hyaline cartilage, the regenerative capacity of these injuries is limited. Therefore, several open and arthroscopic techniques have been described to treat osteochondral injuries of the talus and underlying bone marrow lesions. Throughout this review, these treatment options are discussed along with their indications and currently reported outcomes. A commentary on the authors' preferences among these techniques is also provided.

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).

Particulated juvenile cartilage allograft for the treatment of osteochondral lesions of the talus is associated with a high complication rate and a high failure rate at short-term follow-up: A systematic review

PURPOSE

The purpose of this systematic review was to evaluate the clinical and radiological outcomes together with the complication rates and failure rates at short-term follow-up following particulated juvenile cartilage allograft (PJCA) for the management of osteochondral lesions of the talus (OLT).

METHODS

During October 2023, the PubMed, Embase and Cochrane library databases were systematically reviewed to identify clinical studies examining outcomes following PJCA for the management of OLTs. Data regarding study characteristics, patient demographics, lesion characteristics, subjective clinical outcomes, radiological outcomes, complications and failures were extracted and analysed.

RESULTS

Twelve studies were included. In total, 241 patients underwent PJCA for the treatment of OLT at a weighted mean follow-up of 29.0 ± 24.9 months. The weighted mean lesion size was 138.3 ± 59.6 mm2 . Prior surgical intervention was recorded in seven studies, the most common of which was microfracture (65.9%). The weighted mean American Orthopaedic Foot and Ankle Society score improved from a preoperative score of 58.5 ± 3.2 to a postoperative score of 83.9 ± 5.3. The weighted mean postoperative magnetic resonance observation of cartilage repair tissue (MOCART) score was 48.2 ± 3.3. The complication rate was 25.2%, the most common of which was allograft hypertrophy (13.2%). Thirty failures (12.4%) were observed at a weighted mean time of 9.8 ± 9.6 months following the index procedure.

CONCLUSION

This systematic review demonstrated a moderate improvement in subjective clinical outcomes following PJCA for the treatment of OLT at short term follow-up. However, postoperative MOCART scores were reported as poor. In addition, a high complication rate (25.2%) and a high failure rate (12.4%) at short-term follow-up was observed, calling into question the efficacy of PJCA for the treatment of large OLTs. In light of the available evidence, PJCA for the treatment of large OLTs cannot be currently recommended.

LEVEL OF EVIDENCE

Level IV.

Research progress of procyanidins in repairing cartilage injury after anterior cruciate ligament tear

Anterior cruciate ligament (ACL) tear is a common sports-related injury, and cartilage injury always emerges as a serious complication following ACL tear, significantly impacting the physical and psychological well-being of affected individuals. Over the years, efforts have been directed toward finding strategies to repair cartilage injury after ACL tear. In recent times, procyanidins, known for their anti-inflammatory and antioxidant properties, have emerged as potential key players in addressing this concern. This article focuses on summarizing the research progress of procyanidins in repairing cartilage injury after ACL tear. It covers the roles, mechanisms, and clinical significance of procyanidins in repairing cartilage injury following ACL tear and explores the future prospects of procyanidins in this domain. This review provides novel insights and hope for the repair of cartilage injury following ACL tear.

Particulated Juvenile Articular Cartilage Allograft Transplantation for Patellofemoral Defects Shows Favorable Return-to-Sport Rates and Patient-Reported Outcomes

PURPOSE

To report return-to-sport rates, postoperative patient-reported outcomes (PROs), complication rates, and reoperation rates of a cohort of patients undergoing particulated juvenile articular cartilage (PJAC) allograft transplantation for patellofemoral articular cartilage defects.

METHODS

We performed a single-institution retrospective review of all patients with patellofemoral articular cartilage defects who received PJAC allograft transplantation from 2014 to 2022. Baseline demographic characteristics and surgical data, including concomitant surgical procedures, were collected. Clinical outcomes recorded included return-to-sport rates, complications, reoperations, and the following PRO scores: Kujala knee score, Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Interference score, and PROMIS Physical Function score.

RESULTS

Forty-one knees with a mean age of 23.4 ± 9.7 years and mean follow-up period of 30.3 months (range, 12-107 months) were included. The mean postoperative PROMIS Pain Interference, PROMIS Physical Function, and Kujala knee scores were 47.4 ± 7.7, 52.2 ± 10.8, and 81.7 ± 16.1, respectively, reflecting low residual anterior knee pain and a return to normal function. For patients playing organized sports at the high school and collegiate levels, the overall return-to-sport rate was 100% (17 of 17). During follow-up, complications developed in 12 knees (29.3%), the most common of which was anterior-based knee pain, and 6 knees (14.6%) required a total of 8 reoperations, which occurred from 6 to 32 months postoperatively.

CONCLUSIONS

The 100% return-to-sport rate and satisfactory PRO scores in our study suggest that PJAC allograft transplantation can effectively address patellofemoral cartilage defects in many patients. The complication and reoperation rates of 29.3% and 14.6%, respectively, are consistent with the challenging and heterogeneous etiology and treatment of patellofemoral articular defects.

LEVEL OF EVIDENCE

Level IV, case series.

Open Treatment of Osteochondral Lesions of the Talus With Bone Grafting and Particulated Juvenile Cartilage Allografting

BACKGROUND

Large cystic osteochondral lesions of the talus (OLT) are challenging pathological conditions to treat, but particulated juvenile cartilage allografts (PJCAs) supplemented with bone grafts are a promising therapeutic option. The purpose of this project was to further elucidate the role of PJCA with concomitant bone autografts for treating large cystic OLTs with extensive subchondral bone involvement (greater than 150 mm2 in area and/or deeper than 5 mm).

METHODS

We identified 6 patients with a mean OLT area of 307.2 ± 252.4 mm2 and a mean lesion depth of 10.85 ± 6.10 mm who underwent DeNovo PJCA with bone autografting between 2013 and 2017. Postoperative outcomes were assessed with radiographs, Foot and Ankle Outcome Scores (FAOS), and visual pain scale scores.

RESULTS

At final follow-up (27.0 ± 12.59 weeks), all patients had symptomatic improvement and incorporation of the graft on radiographs. At an average of 62 ± 20.88 months postoperatively, no patients required a revision surgery. All patients contacted by phone in 2018 and 2020 reported they would do the procedure again in retrospect and reported an improvement in their symptoms relative to their preoperative state, especially with pain and in the FAOS activities of daily living subsection (91.93 ± 9.04 in 2018, 74.63 ± 26.86 in 2020).

CONCLUSION

PJCA with concomitant bone autograft is a viable treatment option for patients with large cystic OLTs.

LEVELS OF EVIDENCE

Level IV.

The autologous chondral platelet-rich plasma matrix implantation. A new therapy in cartilage repair and regeneration: macroscopic and biomechanical study in an experimental sheep model

Introduction

Articular cartilage injuries are a severe problem, and the treatments for these injuries are complex. The present study investigates a treatment for full-thickness cartilage defects called Autologous Chondral Platelet Rich Plasma Matrix Implantation (PACI) in a sheep model.

Methods

Chondral defects 8 mm in diameter were surgically induced in the medial femoral condyles of both stifles in eight healthy sheep. Right stifles were treated with PACI and an intraarticular injection with a plasma rich in growth factors (PRGF) solution [treatment group (TRT)], while an intraarticular injection of Ringer's lactate solution was administered in left stifles [Control group (CT)]. The limbs' function was objectively assessed with a force platform to obtain the symmetry index, comparing both groups. After 9 and 18 months, the lesions were macroscopically evaluated using the International Cartilage Repair Society and Goebel scales.

Results

Regarding the symmetry index, the TRT group obtained results similar to those of healthy limbs at 9 and 18 months after treatment. Regarding the macroscopic assessment, the values obtained by the TRT group were very close to those of normal cartilage and superior to those obtained by the CT group at 9 months.

Conclusion

This new bioregenerative treatment modality can regenerate hyaline articular cartilage. High functional outcomes have been reported, together with a good quality repair tissue in sheep. Therefore, PACI treatment might be a good therapeutic option for full-thickness chondral lesions.

Cartilage Tissue Engineering in Practice: Preclinical Trials, Clinical Applications, and Prospects

Articular cartilage defects significantly compromise the quality of life in the global population. Although many strategies are needed to repair articular cartilage, including microfracture, autologous osteochondral transplantation, and osteochondral allograft, the therapeutic effects remain suboptimal. In recent years, with the development of cartilage tissue engineering, scientists have continuously improved the formulations of therapeutic cells, biomaterial-based scaffolds, and biological factors, which have opened new avenues for better therapeutics of cartilage lesions. This review focuses on advances in cartilage tissue engineering, particularly in preclinical trials and clinical applications, prospects, and challenges.

The Dual-Responsive Interaction of Particulated Hyaline Cartilage and Plasma Rich in Growth Factors (PRGF) in the Repair of Cartilage Defects: An In Vitro Study

The treatment of chondral and osteochondral defects is challenging. These types of lesions are painful and progress to osteoarthritis over time. Tissue engineering offers tools to address this unmet medical need. The use of an autologous cartilage construct consisting of hyaline cartilage chips embedded in plasma rich in growth factors (PRGF) has been proposed as a therapeutic alternative. The purpose of this study was to dig into the potential mechanisms behind the in vitro remodelling process that might explain the clinical success of this technique and facilitate its optimisation. Chondrocyte viability and cellular behaviour over eight weeks of in vitro culture, type II collagen synthesis, the dual delivery of growth factors by hyaline cartilage and PRGF matrix, and the ultrastructure of the construct and its remodelling were characterised. The main finding of this research is that the cartilage fragments embedded in the three-dimensional PRGF scaffold contain viable chondrocytes that are able to migrate into the fibrin network, proliferate and synthesise extracellular matrix after the second week of in vitro culture. The characterization of this three-dimensional matrix is key to unravelling the molecular kinetics responsible for its efficacy.

Arthroscopic Cartilage Transplantation

Arthroscopic cartilage repair has made several strides in recent years; however, no gold standard for cartilage restoration has been found. Simple treatment with bone marrow stimulation such as microfracture have shown good short-term results; however, concerns for long-term stability of cartilage repair as well as the subchondral bone health remain in question. Treatment of these lesions often comes down to surgeon preference, the aim of this study is to discuss some of the current options available on the market to further assist surgeons in their decision-making process.

Effects of Electrical Stimulation on Articular Cartilage Regeneration with a Focus on Piezoelectric Biomaterials for Articular Cartilage Tissue Repair and Engineering

There is increasing evidence that chondrocytes within articular cartilage are affected by endogenous force-related electrical potentials. Furthermore, electrical stimulation (ES) promotes the proliferation of chondrocytes and the synthesis of extracellular matrix (ECM) molecules, which accelerate the healing of cartilage defects. These findings suggest the potential application of ES in cartilage repair. In this review, we summarize the pathogenesis of articular cartilage injuries and the current clinical strategies for the treatment of articular cartilage injuries. We then focus on the application of ES in the repair of articular cartilage in vivo. The ES-induced chondrogenic differentiation of mesenchymal stem cells (MSCs) and its potential regulatory mechanism are discussed in detail. In addition, we discuss the potential of applying piezoelectric materials in the process of constructing engineering articular cartilage, highlighting the important advances in the unique field of tissue engineering.

Particulate cartilage and platelet-rich plasma treatment for knee chondral defects in sheep

PURPOSE

Articular cartilage is vulnerable to multiple types of damage and it has limited reparative and regenerative capacities due to its absence of vascularity. Although a large number of therapeutic strategies exist to treat chondral defects, they have some limitations, such as fibrocartilage formation. Therefore, the goal of the present study was to evaluate the chondrogenic regenerative properties of an autologous-made matrix of particulated cartilage and platelet-rich plasma (PACI + PRP) implantation for the treatment of full-thickness chondral defects in sheep.

METHODS

A full-thickness 8 mm diameter cartilage defect was created in the weight-bearing area of the medial femoral condyle in both knees of 16 sheep. The right knees of all animals were treated with particulated autograft cartilage implantation and platelet-rich plasma, while the left knees were injected with Ringer's lactate solution or hyaluronic acid. The sheep were killed 9 or 18 months after surgery. Macroscopic evaluations were performed using three different scoring systems, and histopathological evaluations were performed using a modified scoring system based on different scoring systems.

RESULTS

The PACI + PRP groups showed statistically significant differences in the percentage of defect repair and chondrocytes in the newly formed cartilage tissue at 18 months compared to 9 months.

CONCLUSIONS

The results suggest that macroscopic appearance, histological structure and chondrocyte repair were improved when using PACI + PRP treatment for chondral defects, producing an outcome similar to the surrounding healthy cartilage. PACI + PRP is a totally autologous, easy, and unexpensive treatment that can be performed in one-step procedure and is useful as a therapeutic option for knee chondral defects.

Pulsed Electromagnetic Field Therapy and Direct Current Electric Field Modulation Promote the Migration of Fibroblast-like Synoviocytes to Accelerate Cartilage Repair In Vitro

Articular cartilage injuries are a common source of joint pain and dysfunction. As articular cartilage is avascular, it exhibits a poor intrinsic healing capacity for self-repair. Clinically, osteochondral grafts are used to surgically restore the articular surface following injury. A significant challenge remains with the repair properties at the graft-host tissue interface as proper integration is critical toward restoring normal load distribution across the joint. A key to addressing poor tissue integration may involve optimizing mobilization of fibroblast-like synoviocytes (FLS) that exhibit chondrogenic potential and are derived from the adjacent synovium, the specialized connective tissue membrane that envelops the diarthrodial joint. Synovium-derived cells have been directly implicated in the native repair response of articular cartilage. Electrotherapeutics hold potential as low-cost, low-risk, non-invasive adjunctive therapies for promoting cartilage healing via cell-mediated repair. Pulsed electromagnetic fields (PEMFs) and applied direct current (DC) electric fields (EFs) via galvanotaxis are two potential therapeutic strategies to promote cartilage repair by stimulating the migration of FLS within a wound or defect site. PEMF chambers were calibrated to recapitulate clinical standards (1.5 ± 0.2 mT, 75 Hz, 1.3 ms duration). PEMF stimulation promoted bovine FLS migration using a 2D in vitro scratch assay to assess the rate of wound closure following cruciform injury. Galvanotaxis DC EF stimulation assisted FLS migration within a collagen hydrogel matrix in order to promote cartilage repair. A novel tissue-scale bioreactor capable of applying DC EFs in sterile culture conditions to 3D constructs was designed in order to track the increased recruitment of synovial repair cells via galvanotaxis from intact bovine synovium explants to the site of a cartilage wound injury. PEMF stimulation further modulated FLS migration into the bovine cartilage defect region. Biochemical composition, histological analysis, and gene expression revealed elevated GAG and collagen levels following PEMF treatment, indicative of its pro-anabolic effect. Together, PEMF and galvanotaxis DC EF modulation are electrotherapeutic strategies with complementary repair properties. Both procedures may enable direct migration or selective homing of target cells to defect sites, thus augmenting natural repair processes for improving cartilage repair and healing.

Minced Cartilage Is a One-Step Cartilage Repair Procedure for Small Defects in the Knee-A Systematic-Review and Meta-Analysis

Purpose: Approximately 60% of patients undergoing arthroscopy of the knee present with chondral defects. If left untreated, osteochondral lesions can trigger an early onset of osteoarthritis. Many cartilage repair techniques are mainly differentiated in techniques aiming for bone marrow stimulation, or cell-based methods. Cartilage repair can also be categorized in one- and two-stage procedures. Some two-stage procedures come with a high cost for scaffolds, extensive cell-processing, strict regulatory requirements, and limited logistical availability. Minced cartilage, however, is a one-stage procedure delivering promising results in short term follow-up, as noted in recent investigations. However, there is no available literature summarizing or synthesizing clinical data. The purpose of this study was to analyze and synthesize data from the latest literature in a meta-analysis of outcomes after the minced cartilage procedure and to compare its effectiveness to standard repair techniques. Methods: We conducted a systematic review searching the Cochrane, PubMed, and Ovid databases. Inclusion criteria were the modified Coleman methodology Score (mCMS) >60, cartilaginous knee-joint defects, and adult patients. Patient age < 18 years, biomechanical and animal studies were excluded. Relevant articles were reviewed independently by referring to title and abstract. In a systematic review, we compared three studies and 52 patients with a total of 63 lesions. Results: Analysis of Knee Injury and Osteoarthritis Outcome Score (KOOS) sub scores at 12 and 24 months showed a significant score increase in every sub score. Highest mean difference was seen in KOOS sport, lowest in KOOS symptoms (12 month: KOOS sport (Mean difference: 35.35 [28.16, 42.53]; p < 0.0001), lowest in KOOS symptoms (Mean difference: 20.12 [15.43, 24.80]; p < 0.0001)). A comparison of International Knee Documentation Committee (IKDC ) scores visualized a significant score increase for both time points too ((12 month: pooled total mean: 73.00 ± 14.65; Mean difference: 34.33 [26.84, 41.82]; p < 0.00001) (24 month: pooled total mean: 77.64 ± 14.46; mean difference: 35.20 [39.49, 40.92]; p < 0.00001)). Conclusion: Due to no need for separate cell-processing, and thanks to being a one-step procedure, minced cartilage is a promising method for cartilage repair in small defect sizes (mean 2.77 cm2, range 1.3−4.7 cm2). However, the most recent evidence is scarce, and takes only results two years post-surgery into account. Summarized, minced cartilage presents nearly equal short-term improvement of clinical scores (IKDC, KOOS) compared to standard cartilage repair techniques.

Biologic principles of minced cartilage implantation: a narrative review

Cartilage tissue has a very limited ability to regenerate. Symptomatic cartilage lesions are currently treated by various cartilage repair techniques. Multiple treatment techniques have been proposed in the last 30 years. Nevertheless, no single technique is accepted as a gold standard. Minced cartilage implantation is a newer technique that has garnered increasing attention. This procedure is attractive because it is autologous, can be performed in a single surgery, and is therefore given it is cost-effective. This narrative review provides an overview of the biological potential of current cartilage regenerative repair techniques with a focus on the translational evidence of minced cartilage implantation.

Nonoperative and Operative Soft-Tissue and Cartilage Regeneration and Orthopaedic Biologics of the Foot and Ankle: An Orthoregeneration Network Foundation Review

Orthoregeneration is defined as a solution for orthopaedic conditions that harnesses the benefits of biology to improve healing, reduce pain, improve function, and optimally, provide an environment for tissue regeneration. Options include drugs, surgical intervention, scaffolds, biologics as a product of cells, and physical and electromagnetic stimuli. The goal of regenerative medicine is to enhance the healing of tissue after musculoskeletal injuries as both isolated treatment and adjunct to surgical management, using novel therapies to improve recovery and outcomes. Various orthopaedic biologics (orthobiologics) have been investigated for the treatment of pathology involving the foot and ankle (including acute traumatic injuries and fractures, tumor, infection, osteochondral lesions, arthritis, and tendinopathy) and procedures, including osteotomy or fusion. Promising and established treatment modalities include 1) bone-based therapies (such as cancellous or cortical autograft from the iliac crest, proximal tibia, and/or calcaneus, fresh-frozen or freeze-dried cortical or cancellous allograft, including demineralized bone matrix putty or powder combined with growth factors, and synthetic bone graft substitutes, such as calcium sulfate, calcium phosphate, tricalcium phosphate, bioactive glasses (often in combination with bone marrow aspirate), and polymers; proteins such as bone morphogenic proteins; and platelet-derived growth factors; 2) cartilage-based therapies such as debridement, bone marrow stimulation (such as microfracture or drilling), scaffold-based techniques (such as autologous chondrocyte implantation [ACI] and matrix-induced ACI, autologous matrix-induced chondrogenesis, matrix-associated stem cell transplantation, particulated juvenile cartilage allograft transplantation, and minced local cartilage cells mixed with fibrin and platelet rich plasma [PRP]); and 3) blood, cell-based, and injectable therapies such as PRP, platelet-poor plasma biomatrix loaded with mesenchymal stromal cells, concentrated bone marrow aspirate, hyaluronic acid, and stem or stromal cell therapy, including mesenchymal stem cell allografts, and adipose tissue-derived stem cells, and micronized adipose tissue injections. LEVEL OF EVIDENCE: Level V, expert opinion.

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.

Articular Cartilage Fragmentation Improves Chondrocyte Migration by Upregulating Membrane Type 1 Matrix Metalloprotease

OBJECTIVE

This study was undertaken to elucidate the mechanism of improved chondrocyte migration after juvenile articular cartilage fragmentation.

DESIGN

In vitro organ culture with rabbit cartilage fragments and cell culture with rabbit chondrocytes were performed. In part A, minced juvenile cartilage fragments (~0.5 × 0.5 × 0.5 mm) from rabbits, planted in gelatin sponge and fibrin glue, were cultured for 2, 4, or 6 weeks in vitro and compared with the cartilage chunks (~4 × 4 × 1 mm) and membrane type 1 matrix metalloprotease (MT1-MMP) inhibitor groups. Chondrocyte outgrowth was evaluated on histology and confocal laser scanning microscopy. MT1-MMP expression was compared between the cartilage fragment group and the cartilage chunks group. In part B, articular chondrocytes were harvested from juvenile rabbits, MT1-MMP was transfected into the cells, and cell migration was evaluated using the Transwell and wound healing tests.

RESULTS

The histology and confocal microscopy results revealed that cell accumulation occurred at the edge of cartilage fragments, and outgrowth was better in the cartilage fragment group than those in the cartilage chunks group. Similar results were observed for MT1-MMP expression. After MT1-MMP inhibition, cells did not accumulate at the edge of the cartilage fragments, and chondrocyte outgrowth did not occur. Furthermore, overexpression of MT1-MMP enhanced the migration of articular chondrocytes.

CONCLUSIONS

Juvenile articular cartilage fragmentation improved chondrocyte migration by upregulating MT1-MMP.

Preclinical Evidence of Intra-Articular Autologous Cartilage Micrograft for Osteochondral Repair: Evaluation in a Rat Model

OBJECTIVE

The search for an effective and long-lasting strategy to treat osteochondral defects (OCD) is a great challenge. Regenerative medicine launched a new era of research in orthopaedics for restoring normal tissue functions. The aim of this study was to test the healing potential of Rigenera micrografting technology in a rat model of OCD by investigating 2 cartilage donor sites.

METHODS

Full-thickness OCD was bilaterally created in the knee joints of rats. Animals were randomly divided into 2 groups based on the anatomical site used for micrograft collection: articular (TO) and xiphoid (XA). Micrograft was injected into the knee via an intra-articular approach. The contralateral joint served as the control. Euthanasia was performed 2 months after the set-up of OCD. Histological evaluations foresaw hematoxylin/eosin and safranin-O/fast green staining, the modified O'Driscoll score, and collagen 1A1 and 2A1 immunostaining. Kruskal-Wallis and the post hoc Dunn test were performed to evaluate differences among groups.

RESULTS

Histological results showed defect filling in both autologous micrografts. The TO group displayed tissue repair with more hyaline-like characteristics than its control (P < 0.01). A fibrocartilaginous aspect was instead noticed in the XA group. Immunohistochemical assessments on type 2A1 and type 1 collagens confirmed the best histological results in the TO group.

CONCLUSIONS

TO and XA groups contributed to a different extent to fill the OCD lesions. TO group provided the best histological and immunohistochemical results; therefore, it could be a promising method to treat OCD after the validation in a larger animal model.

Human adipose-derived stromal/stem cells expressing doublecortin improve cartilage repair in rabbits and monkeys

Localized cartilage lesions in early osteoarthritis and acute joint injuries are usually treated surgically to restore function and relieve pain. However, a persistent clinical challenge remains in how to repair the cartilage lesions. We expressed doublecortin (DCX) in human adipose-derived stromal/stem cells (hASCs) and engineered hASCs into cartilage tissues using an in vitro 96-well pellet culture system. The cartilage tissue constructs with and without DCX expression were implanted in the knee cartilage defects of rabbits (n = 42) and monkeys (n = 12). Cohorts of animals were euthanized at 6, 12, and 24 months after surgery to evaluate the cartilage repair outcomes. We found that DCX expression in hASCs increased expression of growth differentiation factor 5 (GDF5) and matrilin 2 in the engineered cartilage tissues. The cartilage tissues with DCX expression significantly enhanced cartilage repair as assessed macroscopically and histologically at 6, 12, and 24 months after implantation in the rabbits and 24 months after implantation in the monkeys, compared to the cartilage tissues without DCX expression. These findings suggest that hASCs expressing DCX may be engineered into cartilage tissues that can be used to treat localized cartilage lesions.

Early Efficacy of Type I Collagen-Based Matrix-Assisted Autologous Chondrocyte Transplantation for the Treatment of Articular Cartilage Lesions

Background: Articular cartilage is a complex structure that allows for low frictional gliding and effective shock absorption. Various sports injuries and inflammatory conditions can lead to lesions in the articular cartilage, which has limited regenerative potential. Type I collagen combined with autologous chondrocytes in a three-dimensional culture were used to induce the regeneration of single-layer autologous expanded chondrocytes without chondrogenic differentiation. Purpose: To assess the clinical, radiological, and histological changes following collagen-based autologous chondrocyte transplantation (MACT) for chondral knee lesions. Methods: The study prospectively enrolled 20 patients with symptomatic knee chondral lesions (mean size lesion was 2.41 ± 0.43 cm², range: 2.0-3.4 cm²) in the lateral femoral condyle and femoral groove who underwent type I collagen-based MACT between July 2017 and July 2019. knee injury and osteoarthritis outcome score (KOOS) was assessed before the procedure, and periodic clinical follow-up was conducted every 3 months for a maximum of 12 months following the procedure and at 1-year intervals thereafter. Magnetic resonance imaging (MRI) T2 mapping of repaired cartilage was also used for the quantitative analysis of regeneration. In one patient, second-look arthroscopy was performed to assess cartilage regeneration characteristics, and a portion of regenerated cartilage was harvested for histological evaluation 12 months after implantation. Results: At pre-operation and at three, six, 12, and 24 months after the operation, KOOS pain, symptoms, daily life activities, sports and recreation, as well as the quality of life were significantly improved between every two time points. Hematoxylin and eosin (HE) staining indicated that the newly formed cartilage was comprised of naive chondrocytes. Safranin O-fast (S-O) green staining of the regenerated tissue revealed fibroblast-like cells surrounded by glycosaminoglycans. Immunohistochemistry (IHC) analysis indicated that collagen type II was uniformly distributed at the deep zone of articular cartilage and type I collagen mainly depositing in the superficial cartilage layer. The T2 values for repaired tissue gradually decreased, eventually approaching near-average values. Conclusion: The present study demonstrated that type I collagen-based MACT is a clinically effective treatment for improving functionality and pain levels. Histological evidence confirmed hyaline cartilage induction and showed that repaired cartilage tended to emerge from the deep to the superficial layer. The quantitative MRI T2 mapping test indicated that there still was a difference between the transplanted cartilage and the surrounding hyaline cartilage. Taken together, the current method represents an efficient approach for the restoration of knee cartilage lesions.

Comparison between Intra-Articular Injection of Infrapatellar Fat Pad (IPFP) Cell Concentrates and IPFP-Mesenchymal Stem Cells (MSCs) for Cartilage Defect Repair of the Knee Joint in Rabbits

Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic method in regenerative medicine. Our previous research adopted a simple nonenzymatic strategy for the preparation of a new type of ready-to-use infrapatellar fat pad (IPFP) cell concentrates. The aim of this study was to compare the therapeutic efficacy of intra-articular (IA) injection of autologous IPFP cell concentrates and allogeneic IPFP-MSCs obtained from these concentrates in a rabbit articular cartilage defect model. IPFP-MSCs sprouting from the IPFP cell concentrates were characterized via flow cytometry as well as based on their potential for differentiation into adipocytes, osteoblasts, and chondrocytes. In the rabbit model, cartilage defects were created on the trochlear groove, followed by treatment with IPFP cell concentrates, IPFP-MSCs, or normal saline IA injection. Distal femur samples were evaluated at 6 and 12 weeks posttreatment via macroscopic observation and histological assessment based on the International Cartilage Repair Society (ICRS) macroscopic scoring system as well as the ICRS visual histological assessment scale. The macroscopic score and histological score were significantly higher in the IPFP-MSC group compared to the IPFP cell concentrate group at 12 weeks. Further, both treatment groups had higher scores compared to the normal saline group. In comparison to the latter, the groups treated with IPFP-MSCs and IPFP cell concentrates showed considerably better cartilage regeneration. Overall, IPFP-MSCs represent an effective therapeutic strategy for stimulating articular cartilage regeneration. Further, due to the simple, cost-effective, nonenzymatic, and safe preparation process, IPFP cell concentrates may represent an effective alternative to stem cell-based therapy in the clinic.

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.

Five-Year Outcome of 1-Stage Cell-Based Cartilage Repair Using Recycled Autologous Chondrons and Allogenic Mesenchymal Stromal Cells: A First-in-Human Clinical Trial

BACKGROUND

Long-term clinical evaluation of patient outcomes can steer treatment choices and further research for cartilage repair. Using mesenchymal stromal cells (MSCs) as signaling cells instead of stem cells is a novel approach in the field.

PURPOSE

To report the 5-year follow-up of safety, clinical efficacy, and durability after treatment of symptomatic cartilage defects in the knee with allogenic MSCs mixed with recycled autologous chondrons in first-in-human study of 1-stage cartilage repair.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study is an investigator-driven study aiming at the feasibility and safety of this innovative cartilage repair procedure. Between 2013 and 2014, a total of 35 patients (mean ± SD age, 36 ± 8 years) were treated with a 1-stage cartilage repair procedure called IMPACT (Instant MSC Product Accompanying Autologous Chondron Transplantation) for a symptomatic cartilage defect on the femoral condyle or trochlear groove. Subsequent follow-up after initial publication was performed annually using online patient-reported outcome measures with a mean follow-up of 61 months (range, 56-71 months). Patient-reported outcome measures included the KOOS (Knee injury and Osteoarthritis Outcome Score), visual analog scale for pain, and EuroQol-5 Dimensions. All clinical data and serious adverse events, including additional treatment received after IMPACT, were recorded. A failure of IMPACT was defined as a chondral defect of at least 20% of the index lesion with a need for a reintervention including a surgical procedure or an intra-articular injection.

RESULTS

Using allogenic MSCs, no signs of a foreign body response or serious adverse reactions were recorded after 5 years. The majority of patients showed statistically significant and clinically relevant improvement in the KOOS and all its subscales from baseline to 60 months: overall, 57.9 ± 16.3 to 78.9 ± 17.7 (P < .001); Pain, 62.3 ± 18.9 to 79.9 ± 20.0 (P = .03); Function, 61.6 ± 16.5 to 79.4 ± 17.3 (P = .01); Activities of Daily Living, 69.0 ± 19.0 to 89.9 ± 14.9 (P < .001); Sports and Recreation, 32.3 ± 22.6 to 57.5 ± 30.0 (P = .02); and Quality of Life, 25.9 ± 12.9 to 55.8 ± 26.8 (P < .001). The visual analog scale score for pain improved significantly from baseline (45.3 ± 23.6) to 60 months (15.4 ± 13.4) (P < .001). Five cases required reintervention.

CONCLUSION

This is the first study showing the midterm safety and efficacy of the proof of concept that allogenic MSCs augment 1-stage articular cartilage repair. The absence of serious adverse events and the clinical outcome support the longevity of this unique concept. These data support MSC-augmented chondron transplantation (IMPACT) as a safe 1-stage surgical solution that is considerably more cost-effective and a logistically advantageous alternative to conventional 2-stage cell-based therapy for articular chondral defects in the knee.

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.

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.