Repair of an Osteochondral Defect With Minced Cartilage Embedded in Atelocollagen Gel: A Rabbit Model

Autologous platelet-rich plasma and fibrin-augmented minced cartilage implantation in chondral lesions of the knee leads to good clinical and radiological outcomes after more than 12 months: A retrospective cohort study of 71 patients

Purpose

The treatment of cartilage lesions remains a challenge. Matrix-associated autologous chondrocyte implantation has evolved to become the gold standard procedure. However, this two-step procedure has crucial disadvantages, and the one-step minced cartilage procedure has gained attention. This retrospective study aimed to evaluate the clinical and radiological outcome of an all-autologous minced cartilage technique in cartilage lesions at the knee joint.

Methods

In this retrospective cohort study, 71 patients (38.6 years ± 12.0, 39,4% female) with a magnetic resonance imaging (MRI) confirmed grade III-IV cartilage defect at the medial femur condyle (n = 20), lateral femur condyle (n = 2), lateral tibia plateau (n = 1), retropatellar (n = 28) and at the trochlea (n = 20) were included. All patients were treated with an all-autologous minced cartilage procedure (AutoCart™). Clinical knee function was evaluated by the Tegner score, visual analogue scale, the subjective and objective evaluation form of the International Knee Documentation Committee and the Knee Injury and Osteoarthritis Outcome Score (KOOS). MRI analyses were performed by magnetic resonance observation of cartilage repair tissue (MOCART) 2.0 knee score. Follow-up examination was 13.7 ± 4.2 (12-24) months postoperative.

Results

All clinical scores significantly improved after surgical intervention (p < 0.0001), especially the subgroup sports and recreation of KOOS showed clear changes from baseline in the follow-up examination. In the postoperative MRI evaluation, 39 of 71 patients showed a complete fill of the cartilage defect without subchondral changes in 78% of the patients in the MOCART 2.0 score in the follow-up analysis. None of the patients showed adverse effects, which are linked to the minced cartilage procedure during the time of follow-up.

Conclusion

An all-autologous minced cartilage technique for chondral lesions at the knee joint seems to be an effective and safe treatment method with good clinical and radiological short-term results.

Level of Evidence

Level IV.

Arthroscopic Shaver-based Harvest of Minced Cartilage Results in Reduced Chondrocyte Viability and Reduced Quality of Cartilaginous Repair Tissue Compared With Open Harvest and Conventional Fragmentation

PURPOSE

To characterize and compare the quality of regenerative cartilage tissue (ReCT) after conventional minced cartilage (CMC) and arthroscopic minced cartilage (AMC), in terms of cell viability, gene expression, and matrix synthesis and to investigate the influence of different shaver types.

METHODS

Chondral tissue was harvested from the knees of 8 porcine donors. Porcine specimens were euthanized one day before harvest. AMC was created with 2 shaver blades in 2 operating modes (oscillating vs forward) and compared with a scalpel-fragmented CMC control. Before histologic analysis, 50% of the tissue was digested to prevent dedifferentiation of chondrocytes to fibroblasts. Cells were cultured and analyzed for cell viability, gene expression of cartilage-specific markers (aggrecan [ACAN], collagen type II, alpha1 [COL2A1], collagen type I, alpha1 [COL1A1], fibronectin-1 [FN1]), and matrix synthesis (Alcian-blue).

RESULTS

AMC tissue contained fewer viable chondrocytes (41%-54% vs 91%; P = .001-.048) compared with CMC. After culture, CMC showed greater expressions of ACAN (27 virtual copy numbers [VCN]/housekeeping gene) and COL2A1 (30 VCN) compared with AMC (ACAN 2-9 VCN, COL2A1 2-7 VCN, P = .001-.039). AMC presented greater expressions of COL1A1 (9-21 VCN) and FN1 (12-17 VCN) than CMC (1 and 6 VCN, P = .001-.050). The signal intensity of the cartilage matrix formed by CMC (86/mm2) was greater than by AMC (7-10 mm2, P = .001-.032).

CONCLUSIONS

CMC contained high numbers of viable chondrocytes, resulting in high-quality, hyaline-like ReCT. In contrast, AMC showed impaired chondrocyte quantity and viability, showing greater expressions of fibroblast markers and a decreased formation of mature cartilage matrix in porcine samples. The high chondrogenic potential of CMC to form hyaline-like ReCT was not confirmed for AMC.

CLINICAL RELEVANCE

On the basis of our findings, arthroscopic harvest of minced cartilage leads to reduced chondrocyte viability and ReCT quality. Accordingly, CMC and AMC cannot be regarded as synonymous techniques, as arthroscopic techniques seem to be less efficacious.

Single-Stage Combined Autologous-Allogenic Cartilage Restoration: Surgical Technique

Articular cartilage injuries in young patients pose a notable treatment dilemma. Multiple reported techniques exist, although some of the most prominent methods currently rely on multiple procedures for chondrocyte harvest and colony expansion prior to implantation. The associated cost and effort this requires limits availability on a global basis, which creates a need for a more widely available cartilage procedure. This Technical Note describes a method for cartilage restoration that incorporates autologous chondrocytes in allogenic extracellular matrix, along with biologic augmentation all performed in a single stage.

Fabrication of atelocollagen-coated bioabsorbable suture and the evaluation of its regenerative efficacy in Achilles tendon healing using a rat experimental model

Recently, the incidence of Achilles tendon ruptures (ATRs) has become more common, and repair surgery using a bioabsorbable suture is generally preferred, particularly in the case of healthy patients. Sutures composed of poly(lactic-co-glycolic acid) (PLGA) are commonly used in ATR surgeries. Nevertheless, owing to the inherent limitations of PLGA, novel bioabsorbable sutures that can accelerate Achilles tendon healing are sought. Recently, several studies have demonstrated the beneficial effects of atelocollagen on tendon healing. In this study, poly(3,4-dihydroxy-L-phenylalanine) (pDOPA), a hydrophilic biomimetic material, was used to modify the hydrophobic surface of a PLGA suture (Vicryl, VC) for the stable coating of atelocollagen on its surface. The main objective was to fabricate an atelocollagen-coated VC suture and evaluate its performance in the healing of Achilles tendon using a rat model of open repair for ATR. Structural analyses of the surface-modified suture indicated that the collagen was successfully coated on the VC/pDOPA suture. Postoperative in vivo biomechanical analysis, histological evaluation, ultrastructural/morphological analyses, and western blotting confirmed that the tendons in the VC/pDOPA/Col group exhibit superior healing than those in the VC and VC/pDOPA groups after 1 and 6 weeks following the surgery. The this study suggests that atelocollagen-coated PLGA/pDOPA sutures are preferable for future medical applications, especially in the repair of ATR.

Osteophyte Cartilage as a Potential Source for Minced Cartilage Implantation: A Novel Approach for Articular Cartilage Repair in Osteoarthritis

Osteoarthritis (OA) is a common joint disorder characterized by cartilage degeneration, often leading to pain and functional impairment. Minced cartilage implantation (MCI) has emerged as a promising one-step alternative for large cartilage defects. However, the source of chondrocytes for MCI remains a challenge, particularly in advanced OA, as normal cartilage is scarce. We performed in vitro studies to evaluate the feasibility of MCI using osteophyte cartilage, which is present in patients with advanced OA. Osteophyte and articular cartilage samples were obtained from 22 patients who underwent total knee arthroplasty. Chondrocyte migration and proliferation were assessed using cartilage fragment/atelocollagen composites to compare the characteristics and regenerative potential of osteophytes and articular cartilage. Histological analysis revealed differences in cartilage composition between osteophytes and articular cartilage, with higher expression of type X collagen and increased chondrocyte proliferation in the osteophyte cartilage. Gene expression analysis identified distinct gene expression profiles between osteophytes and articular cartilage; the expression levels of COL2A1, ACAN, and SOX9 were not significantly different. Chondrocytes derived from osteophyte cartilage exhibit enhanced proliferation, and glycosaminoglycan production is increased in both osteophytes and articular cartilage. Osteophyte cartilage may serve as a viable alternative source of MCI for treating large cartilage defects in OA.

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.

An Atelocollagen Injection Enhances the Healing of Nonoperatively Treated Achilles Tendon Tears: An Experimental Study in Rats

Background

There is growing interest in nonoperative treatment for the management of Achilles tendon ruptures (ATRs). However, nonoperative treatment is limited by the risk of tendon reruptures and low satisfaction rates. Recently, atelocollagen injections have been reported to have beneficial effects on tendon healing.

Purpose

To evaluate the beneficial effects of injected atelocollagen on Achilles tendon healing and investigate the mechanism of atelocollagen on tendon healing.

Study Design

Controlled laboratory study.

Methods

Percutaneous tenotomy of the right Achilles tendon in 66 rats was performed. The animals were equally divided into the noninjection group (NG) and the collagen injection group (CG). At 1, 3, and 6 weeks, the Achilles functional index, cross-sectional area, load to failure, stiffness, stress, and the modified Bonar score were assessed. Transmission electron microscopy, western blotting, and immunohistochemistry were also performed.

Results

The Achilles functional index (-6.8 vs -43.0, respectively; P = .040), load to failure (42.1 vs 27.0 N, respectively; P = .049), and stiffness (18.8 vs 10.3 N/mm, respectively; P = .049) were higher in the CG than those in the NG at 3 weeks. There were no significant differences in histological scores between the 2 groups. Transmission electron microscopy analysis showed that the mean diameter of collagen fibrils in the CG was greater than that in the NG at 3 weeks (117.2 vs 72.6 nm, respectively; P < .001) and 6 weeks (202.1 vs 144.0 nm, respectively; P < .001). Western blot analysis showed that the expression of collagen type I in the CG was higher than that in the NG at 1 week (P = .005) and 6 weeks (P = .001).

Conclusion

An atelocollagen injection had beneficial effects on the healing of nonoperatively treated Achilles tendon injuries. The Achilles tendon of CG rats exhibited better functional, biomechanical, and morphological outcomes compared with NG rats. The molecular data indicated that the mechanism of atelocollagen injections may be associated with an increased amount of collagen type I.

Clinical Relevance

An atelocollagen injection might be a good adjuvant option for the nonoperative treatment of ATRs.

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.

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.

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.

Autologous Minced Cartilage Implantation for Treatment of Chondral and Osteochondral Lesions in the Knee Joint: An Overview

Cartilage defects in the knee are being diagnosed with increased frequency and are treated with a variety of techniques. The aim of any cartilage repair procedure is to generate the highest tissue quality, which might correlate with improved clinical outcomes, return-to-sport, and long-term durability. Minced cartilage implantation (MCI) is a relatively simple and cost-effective technique to transplant autologous cartilage fragments in a single-step procedure. Minced cartilage has a strong biologic potential since autologous, activated non-dedifferentiated chondrocytes are utilized. It can be used both for small and large cartilage lesions, as well as for osteochondral lesions. As it is purely an autologous and homologous approach, it lacks a significant regulatory oversight process and can be clinically adopted without such limitations. The aim of this narrative review is to provide an overview of the current evidence supporting autologous minced cartilage implantation.

Safety and Efficacy of Kartigen® in Treating Cartilage Defects: A Randomized, Controlled, Phase I Trial

Here, we aimed to investigate the safety and preliminary efficacy of Kartigen^®, a matrix with autologous bone marrow mesenchymal stem cell-derived chondrocyte precursors embedded in atelocollagen. As a surgical graft, Kartigen^® was implanted onto the cartilage defects at the weight-bearing site of the medial femoral condyle of the knee. Fifteen patients were enrolled and stratified into two groups, undergoing either Kartigen^® implantation (n = 10) or microfracture (control group, n = 5). The primary endpoint was to evaluate the safety of Kartigen^® by monitoring the occurrence of adverse events through physician queries, physical examinations, laboratory tests, and radiological analyses for 2 years. There were no infections, inflammations, adhesions, loose body, or tumor formations in the Kartigen^®-implanted knees. The preliminary efficacy was assessed using the International Knee Documentation Committee (IKDC) score, visual analog scale, and second-look arthroscopy. The postoperative IKDC scores of the Kartigen^® group significantly improved in the 16th week (IKDC = 62.1 ± 12.8, p = 0.025), kept increasing in the first year (IKDC = 78.2 ± 15.4, p < 0.005), and remained satisfactory in the second year (IKDC = 73.6 ± 13.8, p < 0.005), compared to the preoperative condition (IKDC = 47.1 ± 17.0), while the postoperative IKDC scores of the control group also achieved significant improvement in the 28th week (IKDC = 68.5 ± 6.1, p = 0.032) versus preoperative state (IKDC = 54.0 ± 9.1). However, the IKDC scores decreased in the first year (IKDC = 63.5 ± 11.6) as well as in the second year (IKDC = 52.6 ± 16.4). Thirteen patients underwent second-look arthroscopy and biopsy one year after the operation. The Kartigen^® group exhibited integration between Kartigen^® and host tissue with a smooth appearance at the recipient site, whereas the microfracture group showed fibrillated surfaces. The histological and immunohistochemical analyses of biopsy specimens demonstrated the columnar structure of articular cartilage and existence of collagen type II and glycosaminoglycan mimic hyaline cartilage. This study indicates that Kartigen^® is safe and effective in treating cartilage defects.

Improved Healing of Rabbit Patellar Tendon Defects After an Atelocollagen Injection

BACKGROUND

Patellar tendinopathy is a common cause of limitations in daily life activities in young and/or active people. The patellar tendon consists of a complex of collagen fibers; therefore, collagen could be used as a scaffold in the treatment of patellar tendinopathy.

PURPOSE

To evaluate the healing capacity of injected atelocollagen as a treatment scaffold for patellar tendon defect and, hence, its potential for the treatment of patellar tendinopathy.

STUDY DESIGN

Controlled laboratory study.

METHODS

After receiving a full-thickness patellar tendon defect, 24 New Zealand White rabbits were divided into a control group (without treatment) and an experimental group that received an atelocollagen injection into the defect. Six rabbits from each group were subsequently used for either histologic scoring or biomechanical testing. The Mann-Whitney U test was used to compare histologic evaluation scores and load to failure between the 2 groups. Statistical significance was set at P < .05.

RESULTS

The experimental group showed excellent repair of the damaged patellar tendon and good remodeling of the defective area. In contrast, the control group showed defective healing with loose, irregular matrix fibers and adipose tissue formation. A statistically significant difference was found between the 2 groups in both histologic scores and biomechanical tests at postoperative week 12.

CONCLUSION

Injection of atelocollagen significantly improved the regeneration of damaged patellar tendons.

CLINICAL RELEVANCE

Atelocollagen gel injections could be used to treat patellar tendinopathy in outpatient clinic settings.

Atelocollagen-Embedded Chondrocyte Precursors as a Treatment for Grade-4 Cartilage Defects of the Femoral Condyle: A Case Series with up to 9-Year Follow-Up

We demonstrated the safety and efficacy of autologous chondrocyte precursor (CP) cell therapy in repairing Grade 4 cartilage defects of medial femoral condyles. The autologous bone marrow mesenchymal stem cells of each participant were isolated, amplified, and then differentiated into CPs in atelocollagen. Neotissues made of CPs were implanted into cartilage defects with an average cell density of 4.9 ± 2.1 × 10⁶ cells/cm² through arthrotomy. The knee function was evaluated with the International Knee Documentation Committee (IKDC) subjective knee form. Patients' knee functions significantly improved by the 28th week (IKDC score = 68.3 ± 12.1), relative to the initial functionality before the CP therapy (IKDC score = 46.1 ± 16.4, p-value = 0.0014). Nine of these twelve patients maintained good knee functions for 9 years post-implantation (IKDC score = 69.8 ± 12.3) at levels higher than the pre-implantation values (p-value = 0.0018). Patients were evaluated with MRI and arthroscopy, and the defective sites exhibited a smooth surface without a gap between the implant and host tissue. This study demonstrates that autologous CPs successfully engraft into the host tissue and result in the re-formation of hyaline-like cartilage, thereby improving the impaired knee functions. Most importantly, no adverse event was reported during this long-term follow-up period.

Minced Cartilage Procedure for One-Stage Arthroscopic Repair of Chondral Defects at the Glenohumeral Joint

Chondral defects of the glenohumeral joint are common but still remain a diagnostic and management challenge. Whereas arthroplasty is a reasonable treatment option in the elderly and low-demand population, joint preservation should be aimed for the remaining patients. For larger defects the current gold standard of treatment is autologous chondrocyte implantation. However, disadvantages such as high cost, the restriction in availability of specialized laboratories, and the 2-stage surgical design need to be accounted for if choosing this option. Showing first good clinical results for the knee joint, minced cartilage implantation is moreover a cost-effective procedure bringing autologous cartilage chips harvested from the defect walls and bringing them into the area of damage in a single-step open or arthroscopic approach. We describe an arthroscopic strategy of this technique to treat chondral defects at the glenohumeral joint.

Application of purified porcine collagen in patients with chronic refractory musculoskeletal pain

Background

This study aimed to assess the potential efficacy of purified porcine atelocollagen (PAC) for the management of refractory chronic pain due to suspected connective tissue damage.

Methods

Patients treated with PAC were retrospectively evaluated. Patients with chronic refractory pain, suspected to have originated from musculoskeletal damage or defects with the evidence of imaging studies were included. Pain intensity, using the 11-point numerical rating scale (NRS), was assessed before the procedure, and 1 month after the last procedure.

Results

Eighty-eight patients were finally included for investigation. The mean NRS score was decreased from 5.8 to 4.1 after 1 month of PAC injection (P < 0.001). No independent factor was reported to be directly related to the decrease in NRS score by more than half.

Conclusions

Application of PAC may have potential as a treatment option for refractory chronic musculoskeletal pain. PAC might promote tissue recovery, act as a scaffold for repair, or directly reduce inflammation.