Safety and efficacy of matrix-associated autologous chondrocyte implantation with spheroid technology is independent of spheroid dose after 4 years

Treatment of Large Cartilage Defects in the Knee by Hydrogel-Based Autologous Chondrocyte Implantation: A 5-Year Follow-Up of a Prospective, Multicenter, Single-Arm Phase III Trial

ObjectiveTo evaluate efficacy and safety at 5 years after treatment with hydrogel-based autologous chondrocyte implantation (ACI) for large cartilage defects in the knee.DesignProspective, multicenter, single-arm, Phase III clinical trial. ACI was performed in 100 patients with focal full-thickness cartilage defects ranging from 4 to 12 cm2 in size. The primary outcome measure was the responder rate (defined as improvement by ≥10 points) at 2 years using the Knee Injury and Osteoarthritis Outcome Score (KOOS).ResultsThe preoperative overall KOOS was 39.8 points and continuously increased to 84.7 points at 5 years (mean increase 44.1 points, 95% CI = 40.4-47.9, P < 0.0001). The primary study endpoint (i.e., a KOOS responder rate of >40%) was descriptively met at each assessment timepoint from 3 months to 5 years (Month 3: 75.5%, 95% CI = 65.6-83.8; Year 2: 93.0%, 95% CI = 86.1-97.1, Year 5: 92.8%, 95% CI = 85.7-97.0). International Knee Documentation Committee (IKDC) subjective and objective scores and quality of life assessments (EQ-5D-5L) supported the results seen for the KOOS. The overall treatment failure rate at 5 years was 1%. All treatment-related adverse events were of mild or moderate intensity and mostly occurred within the first year after treatment.ConclusionsHydrogel-based ACI has been shown to be a safe and effective treatment option for patients with large knee cartilage defects with sustained efficacy up to 5 years as demonstrated by consistent and clinically relevant improvements in all investigated efficacy variables. No remarkable adverse events or safety issues were noted.

Correlation and Comparative Evaluation of MOCART and MOCART 2.0 for Assessing Cartilage Repair

Background and Objectives: Chondral and osteochondral lesions can lead to osteoarthritis if untreated, making accurate assessment of cartilage repair outcomes essential for optimizing treatment strategies. The objective of this study was to compare MOCART and MOCART 2.0 and to evaluate the clinical utility of both across different surgical cartilage repair techniques and various time points. Material and Methods: This study included 111 patients (age: 35 ± 10, 35% female) who underwent cartilage repair surgery of the knee between September 2015 and March 2022. A total of 188 postoperative magnetic resonance images were evaluated using MOCART and MOCART 2.0. The correlations between both scores, as well as to the change in Patient-Reported Outcome Measures (PROMs), were determined. Results: MOCART 2.0 scores (66 ± 13) were significantly higher than MOCART scores (58 ± 13, p < 0.001). Positive correlation was observed between scoring systems (r = 0.837, p < 0.001). There was no significant correlation between MOCART or MOCART 2.0 scores and the change in PROMs. Noticeably, there was a statistically significant correlation between both MOCART and MOCART 2.0 in the AutoCart subgroup across multiple timepoints for the change in PROMs. Conclusions: Based on radiographic-clinical outcome discordance, clinicians should not rely solely on MOCART or MOCART 2.0 scores when evaluating cartilage repair success but instead prioritize patient-reported functional improvements while using imaging as a complementary assessment tool.

Cartilage Organoids from Articular Chondroprogenitor Cells and Their Potential to Produce Neo-Hyaline Cartilage

INTRODUCTION

The use of autologous human primary articular chondrocytes (hPACs) for repairing damaged cartilage is the golden standard; however, their 2-dimensional (2D) expansion induces dedifferentiation, making it challenging to create hyaline cartilage. Spinner flasks are efficient for generating cartilage organoids, allowing hPACs to proliferate without dedifferentiation; however, porcine notochordal cell-derived matrix (NCM) is needed for aggregation, limiting clinical application. Human articular chondroprogenitor cells (hACPCs) can be expanded many fold while maintaining chondrogenic potential. Therefore, the scalable production of hACPC cartilage organoids without NCM in spinner flasks was investigated in this study.

METHODS

hPAC organoids with NCM and hACPC organoids using bone morphogenetic protein 9 (BMP-9) were produced in spinner flasks in 14 days. Thereafter, approximately 20 organoids were fused in low adhesive wells for 21 days. Organoids underwent mechanical testing, and both organoids and fused constructs were evaluated using biochemical, histological, and immunohistochemical analysis.

RESULTS

The hACPCs self-assembled and synthesized abundant extracellular matrix once stimulated with BMP-9. The hPAC and hACPC organoids showed similar mechanical properties, but hACPC organoids and fused constructs showed a more uniform matrix and cell distribution.

CONCLUSION

The hACPC organoids fused into a neo-hyaline cartilage-like tissue, demonstrating their potential for improved, scalable cartilage tissue repair.

Arthroscopic Autologous Minced Cartilage Implantation of Cartilage Defects in the Knee: A 2-Year Follow-up of 62 Patients

Background

Symptomatic cartilage defects of the knee joint are frequently diagnosed and can be treated with different available surgical methods. Nevertheless, there is currently no gold standard treatment for all indications. Minced cartilage implantation is increasingly coming into focus as a refined surgical technique.

Purpose

To investigate the 2-year clinical and radiological outcomes of arthroscopic autologous minced cartilage repair with the standardized commercial implantation system AutoCart.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 62 consecutive patients were included and prospectively evaluated preoperatively and at 3, 6, 12, and 24 months postoperatively. Outcomes were assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS) for pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Single Assessment Numeric Evaluation (SANE), and Tegner activity scale at all follow-up time points. The examination of preoperative magnetic resonance imaging (MRI) was performed using the Area Measurement and Depth and Underlying Structures (AMADEUS) score, and the examination of MRI at 24 months was performed using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) 2.0 score.

Results

There were 34 male and 28 female patients (mean age, 38.79 ± 10.78 years) with symptomatic cartilage lesions with a mean defect size of 2.53 ± 1.24 cm2. Lesions were predominantly International Cartilage Repair Society grade 3 located in the region of the femoral condyles. Concomitant surgery was performed in 40.3% of patients. The total KOOS score significantly improved from 62.4 ± 13.1 at baseline to 74.4 ± 15.9 at 24 months (P < .001). The secondary outcome measures of the VAS, WOMAC, and SANE showed a similar pattern, with score improvements in the follow-up period compared to baseline. The mean AMADEUS score was 64.75 ± 13.87, while the mean MOCART 2.0 score was 62.88 ± 9.86, among 20 available patients. The revision surgery rate was 8.1% mainly because of hypertrophy (6.5%).

Conclusion

Among this cohort of patients, minced cartilage implantation demonstrated satisfying 2-year outcomes with increased patient-reported outcome measure scores from 3 to 24 months postoperatively. Regenerated tissue quality on MRI was comparable to that using other cartilage repair methods and showed no associations with patient characteristics or patient-reported outcome measures. Larger cohorts, longer postoperative intervals, and comparable trials are needed to further evaluate the role of this technique in treating cartilage defects.

Effectiveness and Safety of Matrix-Associated Autologous Chondrocyte Implantation for the Treatment of Articular Cartilage Defects: A Real-World Data Analysis in Japan

BACKGROUND

The effectiveness and safety of matrix-associated autologous chondrocyte implantation with an autologous periosteal flap (pMACI) remain unclear. The Japanese Ministry of Health, Labor, and Welfare requires postmarketing surveillance of all patients undergoing pMACI using the tissue-engineered product JACC.

PURPOSE

To evaluate the effectiveness and safety of pMACI for large articular cartilage defects (≥4 cm2) in the knee joint using real-world data analysis.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Data were collected from patients who underwent pMACI between 2012 and 2019, with 2 years of follow-up. The primary outcomes were the Lysholm knee score and Knee injury and Osteoarthritis Outcome Score (KOOS) at 6, 12, and 24 months. Adverse events were assessed by physical examination, magnetic resonance imaging, and/or arthroscopy.

RESULTS

Overall, 232 knees in 225 patients who presented with trauma (198 knees) or osteochondritis dissecans (34 knees) in the medial (132 knees) and lateral (44 knees) femoral condyle, patella (25 knees), trochlea (86 knees), and tibial plateau (4 knees) were included. The mean age of the patients was 40.9 ± 15.0 years, with mean cartilage defects of 5.6 ± 2.4 cm2 in size. Concomitant surgeries, such as osteotomy (50 knees), ligament reconstruction (27 knees), meniscal procedures (28 knees), osteochondral autograft transplantation (24 knees), and microfracture (14 knees), were performed in 113 (48.7%) knees. The minimal clinically important difference in the Lysholm knee score and KOOS Symptoms subscale was achieved in 79.7% and 63.5% of patients, respectively, and the Patient Acceptable Symptom State was achieved in 90.1% and 73.7%, respectively. Substantial clinical benefit was achieved in the KOOS Sports/Recreation and Quality of Life subscales at 39.6% and 37.8%, respectively. Knees that underwent concomitant microfracture had significantly worse KOOS values than the remainder of the cohort. Complications, including effusion (16.8%), graft delamination (14.7%), knee contracture (9.1%), graft hypertrophy (8.2%), and ossification (3.4%), were observed in 86 (37.1%) knees. Osteochondritis dissecans was significantly associated with graft hypertrophy and ossification, whereas concomitant surgery was significantly associated with delamination and contracture. Treatment failure required additional cartilage procedures in 11 (4.7%) knees.

CONCLUSION

Treatment of large cartilage defects (≥4 cm2) with pMACI resulted in improved outcome scores in approximately 75% of patients. However, complications occurred in one-third of patients, and 4.7% required reoperation.

Glycosphingolipids in Osteoarthritis and Cartilage-Regeneration Therapy: Mechanisms and Therapeutic Prospects Based on a Narrative Review of the Literature

Glycosphingolipids (GSLs), a subtype of glycolipids containing sphingosine, are critical components of vertebrate plasma membranes, playing a pivotal role in cellular signaling and interactions. In human articular cartilage in osteoarthritis (OA), GSL expression is known notably to decrease. This review focuses on the roles of gangliosides, a specific type of GSL, in cartilage degeneration and regeneration, emphasizing their regulatory function in signal transduction. The expression of gangliosides, whether endogenous or augmented exogenously, is regulated at the enzymatic level, targeting specific glycosyltransferases. This regulation has significant implications for the composition of cell-surface gangliosides and their impact on signal transduction in chondrocytes and progenitor cells. Different levels of ganglioside expression can influence signaling pathways in various ways, potentially affecting cell properties, including malignancy. Moreover, gene manipulations against gangliosides have been shown to regulate cartilage metabolisms and chondrocyte differentiation in vivo and in vitro. This review highlights the potential of targeting gangliosides in the development of therapeutic strategies for osteoarthritis and cartilage injury and addresses promising directions for future research and treatment.

Comparison of Minced Cartilage Implantation with Autologous Chondrocyte Transplantation in an In Vitro Inflammation Model

The current gold standard to treat large cartilage defects is autologous chondrocyte transplantation (ACT). As a new surgical method of cartilage regeneration, minced cartilage implantation (MCI) is increasingly coming into focus. The aim of this study is to investigate the influence of chondrogenesis between isolated and cultured chondrocytes compared to cartilage chips in a standardized inflammation model with the proinflammatory cytokine TNFα. Articular chondrocytes from bovine cartilage were cultured according to the ACT method to passage 3 and transferred to spheroid culture. At the same time, cartilage was fragmented (<1 mm3) to produce cartilage chips. TNFα (20 ng/mL) was supplemented to simulate an inflammatory process. TNFα had a stronger influence on the passaged chondrocytes compared to the non-passaged ones, affecting gene expression profiles differently between isolated chondrocytes and cartilage chips. MCI showed less susceptibility to TNFα, with reduced IL-6 release and less impact on inflammation markers. Biochemical and histological analyses supported these findings, showing a greater negative influence of TNFα on the passaged pellet cultures compared to the unpassaged cells and MCI constructs. This study demonstrated the negative influence of TNFα on chondrogenesis in a chondrocyte spheroid culture and cartilage fragment model. Passaged chondrocytes are more sensitive to cytokine influences compared to non-passaged cells and chondrons. This suggests that MCI may have superior regeneration potential in osteoarthritic conditions compared to ACT. Further investigations are necessary for the translation of these findings into clinical practice.

Autologous minced cartilage repair for chondral and osteochondral lesions of the knee joint demonstrates good postoperative outcomes and low reoperation rates at minimum five-year follow-up

PURPOSE

Minced cartilage is a one-step, autologous procedure with promising short-term results. The aim of the present study was to evaluate mid-term results in a patient cohort with chondral and osteochondral lesions in the knee joint treated with minced cartilage.

METHODS

From 2015 through 2016, a total of 34 consecutive patients were treated with a single-step, autologous minced cartilage for knee chondral and osteochondral lesions. Numeric analogue scale (NAS) for pain and knee function were obtained prior to surgery and at 12, 24 and 60 months postoperatively. Secondary outcomes, including Lysholm score, Tegner activity score, and the International Knee Documentation Committee (IKDC) score, were recorded at final follow-up. MRI examinations of patients with unplanned radiological follow-up were analysed using the MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score.

RESULTS

A total of 28 patients (44.1% females, age at surgery: 29.5 ± 11.5 years) were available at a mean follow-up of 65.5 ± 4.1 months. Mean defect size was 3.5 ± 1.8 cm2. NAS for pain decreased from a median of 7 (range: 2-10) preoperatively to 2 (0-8) postoperatively. NAS knee function improved from a median of 7 (range: 2-10) to 3 (0-7) after five years, respectively. Satisfactory Lysholm (76.5 ± 12.5), IKDC (71.6 ± 14.8) and Tegner activity (4, range 3-9) scores were reported at final follow-up. Of all patients, 21(75%) and 19 (67.9%) reached or exceeded the PASS for the IKDC- and Lysholm score at final follow-up, respectively. The average overall MOCART 2.0 scores for all postoperatively performed MRIs (n = 23) was 62.3 ± 17.4. Four (14.2%) postoperative complications were directly linked to minced cartilage, one (3.5%) of which required revision surgery.

CONCLUSION

One-step, autologous minced cartilage repair of chondral and osteochondral lesions of the knee without the necessity for subchondral bone treatment demonstrated good patient-reported outcomes, low complication rates, and graft longevity at mid-term follow-up. Minced cartilage represents a viable treatment option to more traditional cartilage repair techniques even in mid-term.

LEVEL OF EVIDENCE

Level III.

Knee Cartilage Lesion Management-Current Trends in Clinical Practice

Many patients, particularly those aged above 40, experience knee joint pain, which hampers both sports activities and daily living. Treating isolated chondral and osteochondral defects in the knee poses a significant clinical challenge, particularly in younger patients who are not typically recommended partial or total knee arthroplasty as alternatives. Several surgical approaches have been developed to address focal cartilage defects. The treatment strategies are characterized as palliation (e.g., chondroplasty and debridement), repair (e.g., drilling and microfracture), or restoration (e.g., autologous chondrocyte implantation, osteochondral autograft, and osteochondral allograft). This review offers an overview of the commonly employed clinical methods for treating articular cartilage defects, with a specific focus on the clinical trials conducted in the last decade. Our study reveals that, currently, no single technology fully meets the essential requirements for effective cartilage healing while remaining easily applicable during surgical procedures. Nevertheless, numerous methods are available, and the choice of treatment should consider factors such as the location and size of the cartilage lesion, patient preferences, and whether it is chondral or osteochondral in nature. Promising directions for the future include tissue engineering, stem cell therapies, and the development of pre-formed scaffolds from hyaline cartilage, offering hope for improved outcomes.

Injectable autologous chondrocyte implantation in acetabular cartilage defects: 2-year minimum clinical and MRI results

INTRODUCTION

Early results using injectable autologous chondrocyte implantation (ACI) for the treatment of full thickness acetabular cartilage defects have been promising. However, so far there is no information on radiological results after injectable ACI using spheroids. The purpose of this sturdy was to (1) investigate the quality of tissue repair on MRI and (2) investigate the correlation between the MRI results and clinical results at a minimum follow-up of 24 months after third generation ACI in full thickness acetabular cartilage defects. It was hypothesized that ACI shows good MRI results in patients with large full thickness acetabular cartilage defects 24 months after surgery. It was also hypothesized that there is a correlation between postoperative clinical and MRI morphological results at a minimum follow-up of 24 months.

STUDY DESIGN

Retrospective case series.

MATERIALS AND METHODS

Patients with ACI for full thickness acetabular cartilage defects > 2 cm² were evaluated by preoperative and postoperative clinical scoring tools including the modified Harris Hip Score (mHHS), the International Hip Outcome Tool (iHOT-33), and the Subjective Hip Value (SHV) as well as a high resolution indirect arthro-MRI 24 months after surgery utilizing an identical imaging protocol for all patients. The magnetic resonance observation of cartilage repair tissue (MOCART) scoring system was used to classify the repair tissue on MRI. Demographic patient data was evaluated for influencing factors for pre- and postoperative clinical as well as radiological results.

RESULTS

Thirty six consecutive patients (5 women/31 men, average age 32.9 years) had undergone two stage ACI procedure. The average size of the cartilage defect was 5.0 (2-6) cm². The average follow-up was 29.9 (24-42) months. Four patients were not available for the final follow-up (follow-up rate 89%). The postoperative average MOCART score was 82.2 (± 14.2). MOCART score showed medium correlation of the item defect fill and the postoperative mHHS (r = 0.384, p = 0.043). There was no correlation of the other items or the total score with postoperative results. The patients showed significant improvement in the outcome measurements between preoperative and postoperative in the mHHS, the iHOT-33, and the SHV.

CONCLUSIONS

Despite the large acetabular cartilage defects included in this study, ACI showed good MRI results with complete defect fill in 87.5% after a minimum 24-month follow-up. Statistically significant correlation of MRI and clinical results could only be seen with the item defect fill. Further research with longer follow-up is needed to evaluate the long-term results of ACI in acetabular cartilage defects.

Therapeutic strategies of three-dimensional stem cell spheroids and organoids for tissue repair and regeneration

Three-dimensional (3D) stem cell culture systems have attracted considerable attention as a way to better mimic the complex interactions between individual cells and the extracellular matrix (ECM) that occur in vivo. Moreover, 3D cell culture systems have unique properties that help guide specific functions, growth, and processes of stem cells (e.g., embryogenesis, morphogenesis, and organogenesis). Thus, 3D stem cell culture systems that mimic in vivo environments enable basic research about various tissues and organs. In this review, we focus on the advanced therapeutic applications of stem cell-based 3D culture systems generated using different engineering techniques. Specifically, we summarize the historical advancements of 3D cell culture systems and discuss the therapeutic applications of stem cell-based spheroids and organoids, including engineering techniques for tissue repair and regeneration.

The Most Common Rehabilitation Protocol After Matrix-Assisted Autologous Chondrocyte Implantation Is Immediate Partial Weight-Bearing and Continuous Passive Motion

Purpose

To perform a systematic review of postoperative rehabilitation protocols for third-generation autologous chondrocyte implantation (ACI) of the knee joint.

Methods

A systematic review was performed by searching PubMed, Cochrane Library, and EMBASE to locate randomized controlled trials that described a rehabilitation protocol following third-generation ACI of the knee joint. The search terms used were: "autologous" AND "chondrocyte" AND "randomized". Data extracted from each study included various components of postoperative rehabilitation, such as initial weight-bearing (WB) status and time to full WB, the use of continuous passive motion (CPM), the time to return to sports, and physical therapy (PT) modalities used and the timing of their initiation.

Results

Twenty-five studies (22 Level I, 3 Level II) met inclusion criteria, including a total of 905 patients undergoing treatment with ACI. The average patient age ranged from 29.1 to 54.8 years, and the mean follow-up time ranged from 3 months to 10.0 years. The average lesion size ranged from 1.9 to 5.8 cm², and the most common lesion location was the medial femoral condyle (n = 494). Twenty studies allowed partial WB postoperatively with all studies permitting full WB within 12 weeks. Twenty studies used CPM in their rehabilitation protocols and initiated its use within 24 hours postoperatively. Among 10 studies that reported time to return to sport, 9 (90%) allowed return by 12 months. While most protocols used strength training as well as the inclusion of proprioceptive training, there was disagreement on the timing and inclusion of specific PT modalities used during the rehabilitation process.

Conclusions

Based on the included studies, most rehabilitation protocols for third-generation ACI initiate CPM within 24 hours postoperatively and allow partial WB immediately following surgery with progression to full WB within 12 weeks. There is variation of the PT modalities used as well as the timing of their initiation.

Level of Evidence

Level II, systematic review of Level I-II studies.

Sustained superiority in KOOS subscores after matrix-associated chondrocyte implantation using spheroids compared to microfracture

PURPOSE

To evaluate the safety and efficacy of matrix-associated autologous chondrocyte implantation (ACI) using spheroids in comparison to arthroscopic microfracture for the treatment of symptomatic cartilage defects of the knee.

METHODS

In a prospective multicenter-controlled trial, patients aged between 18 and 50 years, with single symptomatic focal cartilage defects between 1 and 4 cm² (mean 2.6 ± 0.8, median 2.75, range 1.44-5.00) in the knee were randomized to treatment with ACI with spheroids (n = 52) or microfracture (n = 50). Primary clinical outcome was assessed by the Knee Injury and Osteoarthritis Outcome Score (KOOS). Analyses were performed in a defined hierarchical manner where outcomes of ACI were first compared to baseline values followed by a comparison to the microfracture group with repeated-measures ANCOVA with a non-inferiority approach. Subgroup analyses were performed to investigate the influence of age and defect size on the overall KOOS. Secondary clinical outcomes were the magnetic resonance observation of cartilage repair tissue (MOCART), modified Lysholm score and International Knee Documentation Committee (IKDC) examination form. Safety data focused on adverse events. Here the 5 years results are presented at which there were 33 observed cases in the ACI group and 30 in the microfracture group.

RESULTS

The overall KOOS and its five subscores were significantly improved compared to baseline for both the ACI and microfracture group. Non-inferiority of ACI to microfracture was confirmed for the overall KOOS and the subscores, while for the subscores activities of daily living, quality of life and sports and recreation of the threshold for superiority was passed. In the ACI group, a notably more rapid initial improvement of the KOOS was found at three months for the older age group compared to the younger age group and the microfracture group. No other differences were found based on age or defect size. In addition, clinical improvement was found for the MOCART, modified Lysholm and IKDC examination form both the ACI and microfracture group. No safety concern related to either treatment was observed.

CONCLUSION

This study confirms the safety and efficacy of matrix-associated ACI with spheroids at a mid to long-term follow-up. Non-inferiority of ACI to microfracture was confirmed for the overall KOOS and all subscores, while superiority was reached for the subscores activities of daily living, quality of life and sports and recreation in the ACI group. This underlines the importance of ACI for the young and active patients.

LEVEL OF EVIDENCE

I.

Knorpelersatzverfahren und Regeneration am Knie- und Hüftgelenk

Die operative Therapie von Knorpelschäden am Kniegelenk hat sich in den letzten Jahren von vorsichtigen Anfängen mit innovativen Therapieansätzen zu einem festen und etablierten Baustein der gelenkerhaltenden Therapie entwickelt. Hingegen hat sich am Hüftgelenk erst in den letzten 10 Jahren, basierend auf einem erweiterten Verständnis grundlegender mechanischer Pathomechanismen, die gelenkerhaltende Hüftchirurgie und insbesondere die Knorpeltherapie etabliert. Der Beitrag stellt die zur Verfügung stehenden Techniken vor.

Progress of Platelet Derivatives for Cartilage Tissue Engineering

Articular cartilage has limited self-regeneration ability for lacking of blood vessels, nerves, and lymph that makes it a great challenge to repair defects of the tissue and restore motor functions of the injured or aging population. Platelet derivatives, such as platelet-rich plasma, have been proved effective, safe, and economical in musculoskeletal diseases for their autologous origin and rich in growth factors. The combination of platelet derivatives with biomaterials provides both mechanical support and localized sustained release of bioactive molecules in cartilage tissue engineering and low-cost efficient approaches of potential treatment. In this review, we first provide an overview of platelet derivatives and their application in clinical and experimental therapies, and then we further discuss the techniques of the addition of platelet derivatives and their influences on scaffold properties. Advances in cartilage tissue engineering with platelet derivatives as signal factors and structural components are also introduced before prospects and concerns in this research field. In short, platelet derivatives have broad application prospects as an economical and effective enhancement for tissue engineering–based articular cartilage repair.

Pre-culture of human mesenchymal stromal cells in spheroids facilitates chondrogenesis at a low total cell count upon embedding in biomaterials to generate cartilage microtissues

Material-assisted cartilage tissue engineering has limited application in cartilage treatment due to hypertrophic tissue formation and high cell counts required. This study aimed at investigating the potential of human mesenchymal stromal cell (hMSC) spheroids embedded in biomaterials to study the effect of biomaterial composition on cell differentiation. Pre-cultured (3 days, chondrogenic differentiation media) spheroids (250 cells/spheroid) were embedded in tyramine-modified hyaluronic acid (THA) and collagen type I (Col) composite hydrogels (four combinations of THA (12.5 vs 16.7 mg/ml) and Col (2.5 vs 1.7 mg/ml) content) at a cell density of 5 × 10⁶ cells/ml (2 × 10⁴ spheroids/ml). Macropellets derived from single hMSCs (2.5 × 10⁵ cells, ScMP) or hMSC spheroids (2.5 × 10⁵ cells, 10³ spheroids, SpMP) served as control. hMSC differentiation was analyzed using glycosaminoglycan (GAG) quantification, gene expression analysis and (immuno-)histology. Embedding of hMSC spheroids in THA-Col induced chondrogenic differentiation marked by upregulation of aggrecan (ACAN) and COL2A1, and the production of GAGs . Lower THA led to more pronounced chondrogenic phenotype compared to higher THA content. Col content had no significant influence on hMSC chondrogenesis. Pellet cultures showed an upregulation in chondrogenic-associated genes and production of GAGs with less upregulation of hypertrophic-associated genes in SpMP culture compared to ScMP group. This study presents hMSC pre-culture in spheroids as promising approach to study chondrogenic differentiation after biomaterial encapsulation at low total cell count (5 × 10⁶/ml) without compromising chondrogenic matrix production. This approach can be applied to assemble microtissues in biomaterials to generate large cartilage construct. STATEMENT OF SIGNIFICANCE: In vitro studies investigating the chondrogenic potential of biomaterials are limited due to the low cell-cell contact of encapsulated single cells. Here, we introduce the use of pre-cultured hMSC spheroids to study chondrogenesis upon encapsulation in a biomaterial. The use of spheroids takes advantage of the high cell-cell contact within each spheroid being critical in the early chondrogenesis of hMSCs. At a low seeding density of 5·10⁶ cells/ml (2 × 10⁴ spheroids/ml) we demonstrated hMSC chondrogenesis and cartilaginous matrix deposition. Our results indicate that the pre-culture might have a beneficial effect on hypertrophic gene expression without compromising chondrogenic differentiation. This approach has shown potential to assemble microtissues (here spheroids) in biomaterials to generate large cartilage constructs and to study the effect of biomaterial composition on cell alignment and migration.

Limited evidence for biological treatment measures for cartilage and tendon injuries of the shoulder

PURPOSE

To critically review the available literature on the usage of biologics to treat cartilage and tendon injuries of the shoulder.

METHODS

Four different databases were searched in January 2020 for studies reporting data on bone marrow stimulation, autologous chondrocyte implantation, platelet-rich plasma, autologous concentrated serum, and bone marrow aspirate concentrate for the treatment of cartilage and/or tendon injuries of the shoulder. Prospective, retrospective, cohort and case-control studies as well as case series, systematic reviews and laboratory studies (involving human tissue) were included. Cadaveric or animal studies were excluded. Findings were summarized and an expert opinion on trends was provided.

RESULTS

Although there is limited literature available on biologics in cartilage lesions of the shoulder, the advancement from micro- to nanofracture, that is well established for the treatment of cartilage lesions in the knee, may be the next step in the treatment of shoulder lesions as well. The high rate of failure and therefore the complexity of tendon healing following rotator cuff repair has led to a rising interest in biologic augmentation such as platelet-rich plasma and stem cells to enhance tendon-bone-healing and to decrease the prevalence of failure. Despite the increase in publications, there exists a huge heterogeneity of content, quality, and quantity of among studies and their processing methods reporting the use of platelet-rich plasma in rotator cuff repair.

CONCLUSION

Conclusions from individual studies cannot be generalized. Currently, no evidence supports that platelet-rich plasma provides clinical benefits in rotator cuff repair. Similar is reported for microfracture in rotator cuff repair, however, despite no clinical benefits, microfracture has shown to reduce the appearance of structural failures. Although some evidence exists for the use of stem cells form bone marrow aspirate concentrate, results from large case series are still lacking.

LEVEL OF EVIDENCE

Level V.

Treatment of Large Cartilage Defects in the Knee by Hydrogel-Based Autologous Chondrocyte Implantation: Two-Year Results of a Prospective, Multicenter, Single-Arm Phase III Trial

OBJECTIVE

To evaluate the clinical outcome of a hydrogel-based autologous chondrocyte implantation (ACI) for large articular cartilage defects in the knee joint.

DESIGN

Prospective, multicenter, single-arm, phase III clinical trial. ACI was performed in 100 patients with focal full-thickness cartilage defects ranging from 4 to 12 cm² in size. The primary outcome measure was the responder rate at 2 years using the Knee Injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

Two years after ACI treatment, 93% of patients were KOOS responders having improved by ≥10 points compared with their pre-operative level. The primary endpoint of the study was met and demonstrated that the KOOS response rate is markedly greater than 40% with a lower 95% CI (confidence interval) of 86.1, more than twice the pre-specified no-effect level. KOOS improvement (least squares mean) was 42.0 ± 1.8 points (95% CI between 38.4 and 45.7). Mean changes from baseline were significant in the overall KOOS and in all 5 KOOS subscores from Month 3 (first measurement) to Month 24 (inclusive) (P < 0.0001). The mean MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score after 24 months reached 80.0 points (95% CI: 70.0-90.0 points) and 92.1 points in lesions ≤ 5 cm².

CONCLUSIONS

Overall, hydrogel-based ACI proved to be a valuable treatment option for patients with large cartilage defects in the knee as demonstrated by early, statistically significant, and clinically meaningful improvement up to 2 years follow-up. Parallel to the clinical improvements, MRI analyses suggested increasing maturation, re-organization, and integration of the repair tissue.

TRIAL REGISTRATION

NCT03319797; EudraCT No.: 2016-002817-22.

Safety and Efficacy of Matrix-Associated Autologous Chondrocyte Implantation With Spheroids for Patellofemoral or Tibiofemoral Defects: A 5-Year Follow-up of a Phase 2, Dose-Confirmation Trial

Background:

Matrix-associated autologous chondrocyte implantation (ACI) is a well-established treatment for cartilage defects. High-level evidence at midterm follow-up is limited, especially for ACI using spheroids (spherical aggregates of ex vivo expanded human autologous chondrocytes and self-synthesized extracellular matrix).

Purpose:

To assess the safety and efficacy of 3-dimensional matrix-associated ACI using spheroids to treat medium to large cartilage defects on different locations in the knee joint (patella, trochlea, and femoral condyle) at 5-year follow-up.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

A total of 75 patients aged 18 to 50 years with medium to large (4-10 cm²), isolated, single cartilage defects, International Cartilage Repair Society grade 3 or 4, were randomized on a single-blind basis to treatment with ACI at 1 of 3 dose levels: 3 to 7, 10 to 30, or 40 to 70 spheroids/cm² of defect size. Outcomes were assessed via changes from baseline Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee score, and modified Lysholm assessments at 1- and 5-year follow-up. Structural repair was evaluated using MOCART (magnetic resonance observation of cartilage repair tissue) score. Treatment-related adverse events were assessed up to 5 years for all patients. The overall KOOS at 12 months was assessed for superiority versus baseline in a 1-sample, 2-sided t test.

Results:

A total of 73 patients were treated: 24 in the low-dose group, 25 in the medium-dose group, and 24 in the high-dose group. The overall KOOS improved from 57.0 ± 15.2 at baseline to 73.4 ± 17.3 at 1-year follow-up (P < .0001) and 76.9 ± 19.3 at 5-year follow-up (P < .0001), independent of the applied dose. The different defect locations (patella, trochlea, and weightbearing part of the femoral condyles; P = .2216) and defect sizes (P = .8706) showed comparable clinical improvement. No differences between the various doses were observed. The overall treatment failure rate until 5 years was 4%. Most treatment-related adverse events occurred within the first 12 months after implantation, with the most frequent adverse reactions being joint effusion (n = 71), arthralgia (n = 14), and joint swelling (n = 9).

Conclusion:

ACI using spheroids was safe and effective for defect sizes up to 10 cm² and showed maintenance of efficacy up to 5 years for all 3 doses that were investigated.

Registration:

NCT01225575 (ClinicalTrials.gov identifier); 2009-016816-20 (EudraCT number).

Freeze-Dried Curdlan/Whey Protein Isolate-Based Biomaterial as Promising Scaffold for Matrix-Associated Autologous Chondrocyte Transplantation-A Pilot In-Vitro Study

The purpose of this pilot study was to establish whether a novel freeze-dried curdlan/whey protein isolate-based biomaterial may be taken into consideration as a potential scaffold for matrix-associated autologous chondrocyte transplantation. For this reason, this biomaterial was initially characterized by the visualization of its micro- and macrostructures as well as evaluation of its mechanical stability, and its ability to undergo enzymatic degradation in vitro. Subsequently, the cytocompatibility of the biomaterial towards human chondrocytes (isolated from an orthopaedic patient) was assessed. It was demonstrated that the novel freeze-dried curdlan/whey protein isolate-based biomaterial possessed a porous structure and a Young's modulus close to those of the superficial and middle zones of cartilage. It also exhibited controllable degradability in collagenase II solution over nine weeks. Most importantly, this biomaterial supported the viability and proliferation of human chondrocytes, which maintained their characteristic phenotype. Moreover, quantitative reverse transcription PCR analysis and confocal microscope observations revealed that the biomaterial may protect chondrocytes from dedifferentiation towards fibroblast-like cells during 12-day culture. Thus, in conclusion, this pilot study demonstrated that novel freeze-dried curdlan/whey protein isolate-based biomaterial may be considered as a potential scaffold for matrix-associated autologous chondrocyte transplantation.

Short-term radiological results after spheroid-based autologous chondrocyte implantation in the knee are independent of defect localisation

BACKGROUND

Lesions of articular cartilage represent a crucial risk factor for the early development of osteoarthritis. Autologous chondrocyte implantation (ACI) is a well-established procedure in therapy of those lesions in the knee. The aim of the presented study is to detect differences in short-term radiological outcome depending on defect localization (femoral condyle vs. retropatellar) after spheroid-based ACI.

OBJECTIVE

This study aimed to demonstrate that radiological outcome after spheroid-based ACI in the knee is independent of defect localization.

METHODS

MRI-scans after retropatellar ACI and ACI of the medial/lateral femoral condyle, with a preoperative Outerbridge grade of III or IV were evaluated regarding MOCART 2.0.

RESULTS

The mean defect-size was 5.0 ± 1.8 cm2, with a minimum size of 2 cm2 and a maximum size of 9 cm2. Scans were performed 7.7 months (± 3.1 months) postoperatively. The mean MOCART 2.0 score was 78.5 ± 15.6. No statistically significant influence neither of the localization (p= 0.159), the gender (p= 0.124) nor defect size (< 5 cm2 vs. ⩾ 5 cm2; p= 0.201) could be observed.

CONCLUSIONS

The presented data demonstrate good to excellent radiological short-term results after spheroid-based ACI. Data indicates, that at least radiological results are independent of gender, defect-size and defect-localization.

Role of Matrix-Associated Autologous Chondrocyte Implantation with Spheroids in the Treatment of Large Chondral Defects in the Knee: A Systematic Review

Autologous chondrocyte implantation (ACI) is a cell therapy for the treatment of focal cartilage defects. The ACI product that is currently approved for use in the European Union (EU) consists of spheroids of autologous matrix-associated chondrocytes. These spheroids are spherical aggregates of ex vivo expanded human autologous chondrocytes and their self-synthesized extracellular matrix. The aim is to provide an overview of the preclinical and nonclinical studies that have been performed to ensure reproducible quality, safety, and efficacy of the cell therapy, and to evaluate the clinical data on ACI with spheroids. A systematic review was performed to include all English publications on self-aggregated spheroids of chondrocytes cultured in autologous serum without other supplements. A total of 20 publications were included, 7 pre- and nonclinical and 13 clinical research publications. The pre- and nonclinical research publications describe the development from concept to in vivo efficacy and quality- and safety-related aspects such as biodistribution, tumorigenicity, genetic stability, and potency. The evaluation of clinical research shows short- to mid-term safety and efficacy for the ACI with spheroid-based treatment of cartilage defects in both randomized clinical trials with selected patients, as well as in routine treatment providing real-world data in more complex patients.

It is time to crowd your cell culture media - Physicochemical considerations with biological consequences

In vivo, the interior and exterior of cells is populated by various macromolecules that create an extremely crowded milieu. Yet again, in vitro eukaryotic cell culture is conducted in dilute culture media that hardly imitate the native tissue density. Herein, the concept of macromolecular crowding is discussed in both intracellular and extracellular context. Particular emphasis is given on how the physicochemical properties of the crowding molecules govern and determine kinetics, equilibria and mechanism of action of biochemical and biological reactions, processes and functions. It is evidenced that we are still at the beginning of appreciating, let alone effectively implementing, the potential of macromolecular crowding in permanently differentiated and stem cell culture systems.

Bioinspired in vitro microenvironments to control cell fate: focus on macromolecular crowding

The development of therapeutic regenerative medicine and accurate drug discovery cell-based products requires effective, with respect to obtaining sufficient numbers of viable, proliferative, and functional cell populations, cell expansion ex vivo. Unfortunately, traditional cell culture systems fail to recapitulate the multifaceted tissue milieu in vitro, resulting in cell phenotypic drift, loss of functionality, senescence, and apoptosis. Substrate-, environment-, and media-induced approaches are under intense investigation as a means to maintain cell phenotype and function while in culture. In this context, herein, the potential of macromolecular crowding, a biophysical phenomenon with considerable biological consequences, is discussed.

Influence of the Mechanical Environment on the Regeneration of Osteochondral Defects

Articular cartilage is a highly specialised connective tissue of diarthrodial joints which provides a smooth, lubricated surface for joint articulation and plays a crucial role in the transmission of loads. In vivo cartilage is subjected to mechanical stimuli that are essential for cartilage development and the maintenance of a chondrocytic phenotype. Cartilage damage caused by traumatic injuries, ageing, or degradative diseases leads to impaired loading resistance and progressive degeneration of both the articular cartilage and the underlying subchondral bone. Since the tissue has limited self-repairing capacity due its avascular nature, restoration of its mechanical properties is still a major challenge. Tissue engineering techniques have the potential to heal osteochondral defects using a combination of stem cells, growth factors, and biomaterials that could produce a biomechanically functional tissue, representative of native hyaline cartilage. However, current clinical approaches fail to repair full-thickness defects that include the underlying subchondral bone. Moreover, when tested in vivo, current tissue-engineered grafts show limited capacity to regenerate the damaged tissue due to poor integration with host cartilage and the failure to retain structural integrity after insertion, resulting in reduced mechanical function. The aim of this review is to examine the optimal characteristics of osteochondral scaffolds. Additionally, an overview on the latest biomaterials potentially able to replicate the natural mechanical environment of articular cartilage and their role in maintaining mechanical cues to drive chondrogenesis will be detailed, as well as the overall mechanical performance of grafts engineered using different technologies.

Three-dimensional, Scaffold-Free, Autologous Chondrocyte Transplantation: A Systematic Review

Background:

A 3-dimensional, scaffold-free, and completely autologous form of chondrocyte transplantation (ACT3D) has been developed and applied in clinical practice in the past decade to overcome disadvantages of previous-generation procedures.

Purpose:

To document and analyze the available literature on the results of ACT3D in the treatment of articular chondral lesions in the knee and hip joints.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

All studies published in English addressing ACT3D were identified and included those that fulfilled the following criteria: (1) level 1 through 4 evidence, (2) measures of radiological or functional/clinical outcome, and (3) outcome related to cartilage lesions of the knee and hip joints.

Results:

A total of 10 studies were selected: 2 randomized controlled trials, 1 cohort study, and 7 case series. The studies revealed significant increases in patients’ subjective quality of life, satisfaction, pain reduction, and improvement in joint function at short- to medium-term follow-up. Magnetic resonance imaging-assisted examination and second-look arthroscopy showed a hyaline-like repair tissue with a high degree of defect filling and integration.

Conclusion:

ACT3D shows promising results in the therapy of articular cartilage defects in the knee as well as in the hip, but well-designed, long-term studies are lacking. ACT3D might have relevant advantages over common matrix-associated autologous chondrocyte transplantation products, but systematic evaluation and randomized controlled studies are crucial to verify the potential of this tissue-engineered approach.