A Review of Cartilage Defect Treatments Using Chitosan Hydrogels in Experimental Animal Models.

INTRODUCTION: Chitosan (CS) is a polycationic polysaccharide comprising glucosamine and N-acetylglucosamine and constitutes a potential material for use in cartilage tissue engineering. Moreover, CS hydrogels are able to promote the expression of cartilage matrix components and reduce inflammatory and catabolic mediator production by chondrocytes. Although all the positive outcomes, no review has analyzed the effects of CS hydrogels on cartilage repair in animal models. METHODS: This study aimed to review the literature to examine the effects of CS hydrogels on cartilage repair in experimental animal models. The search was done by the descriptors of the Medical Subject Headings (MeSH) defined below: "Chitosan," "hydrogel," "cartilage repair," and "in vivo." A total of 420 articles were retrieved from the databases Pubmed, Scopus, Embase, Lilacs, and Web of Science. After the eligibility analyses, this review reported 9 different papers from the beginning of 2002 through the middle of 2022. RESULTS: It was found that cartilage repair was improved with the treatment of CS hydrogel, especially the one enriched with cells. In addition, CS hydrogel produced an upregulation of genes and proteins that act in the cartilage repair process, improving the biomechanical properties of gait. CONCLUSION: In conclusion, CS hydrogels were able to stimulate tissue ingrowth and accelerate the process of cartilage repair in animal studies.

Suitable characteristics in the selection of human allogeneic chondrocytes donors to increase the number of viable cells for cartilage repair.

Autologous chondrocyte implantation has shown optimal long-term outcomes in the treatment of cartilage lesions. The challenge for a single-stage approach lies in obtaining sufficient number of cells with high viability. The answer could lie in supplementing or replacing them with allogenic chondrocytes coming from cadaveric donors. In the present work, we aimed to compare the number of viable cells isolated from cartilage of live and cadaveric donors and to determine the suitable characteristics of the best donors. A total of 65 samples from donors aged from 17 to 55 years, either women or men, were enrolled in this study (33 living vs. 32 cadaveric). The mean time of hours from death to processing samples in cadaveric donors was higher compared to live donors (64.3 ± 17.7 vs. 4.6±6.4). The number of isolated chondrocytes per gram of cartilage was higher in cadaveric donors (5.389 × 106 compared to 3.067 × 106 in living donors), whereas the average of cell viability was comparable in both groups (84.16% cadaveric, 87.8% alive). It is possible to obtain viable chondrocytes from cartilage harvested from cadaveric donors, reaching a similar cell number and viability to that obtained from the cartilage of living donors.

Etiology of Cartilage Lesions Does Not Affect Clinical Outcomes of Patellofemoral Autologous Chondrocyte Implantation.

OBJECTIVE: To determine the relationship between cartilage lesion etiology and clinical outcomes after second-generation autologous chondrocyte implantation (ACI) in the patellofemoral joint (PFJ) with a minimum of 2 years' follow-up. METHODS: A retrospective review of all patients that underwent ACI in the PFJ by a single surgeon was performed. Seventy-two patients with a mean follow-up of 4.2 ± 2.0 years were enrolled in this study and were stratified into 3 groups based on the etiology of PFJ cartilage lesions: patellar dislocation (group 1; n = 23); nontraumatic lesions, including chondromalacia, osteochondritis dissecans, and degenerative defects (group 2; n = 28); and other posttraumatic lesions besides patellar dislocations (group 3; n = 21). Patient's mean age was 29.6 ± 8.7 years. Patients in group 1 were significantly younger (25.4 ± 7.9 years) than group 2 (31.7 ± 9.6 years; P = 0.025) and group 3 (31.5 ± 6.6 years; P = 0.05). Body mass index averaged 26.2 ± 4.3 kg/m2, with a significant difference between group 1 (24.4 ± 3.2 kg/m2) and group 3 (28.7 ± 4.5 kg/m2; P = 0.005). A clinical comparison was established between groups based on patient-reported outcome measures (PROMs) and failure rates. RESULTS: Neither pre- nor postoperative PROMs differed between groups (P > 0.05). No difference was seen in survivorship between groups (95.7% vs. 82.2% vs. 90.5%, P > 0.05). CONCLUSION: Cartilage lesion etiology did not influence clinical outcome in this retrospective study after second generation ACI in the PFJ. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Arthroscopic Treatment of Patellar and Trochlear Cartilage Lesions with Matrix Encapsulated Chondrocyte Implantation versus Microfracture: Quantitative Assessment with MRI T2-Mapping and MOCART at 4-Year Follow-up.

METHODS: Seventeen patients aged 18 to 55 years with symptomatic full-thickness cartilage lesions on either patella or trochlea were treated with matrix autologous chondrocyte implantation (MACI) or microfracture (MF). Both procedures combined with unloading/realigning techniques. Clinical assessment and T2-mapping were evaluated at 48-months. RESULTS: Clinically results from pre-op to 48-months improved significantly in MACI and MF for Lysholm (p = 0.001, p = 0.001), IKDC-S (p = 0.001, p = 0.002), KOOS-P (p = 0.000, p = 0.002), KOOS-DLA (p = 0.002, p = 0.003), KOOS-Sports/Rec (p = 0.000, p = 0.004), KOOS-QoL (p = 0.000, p = 0.003), KOOS-symptoms (p = 0.001, p = 0.020), and Kujala (p = 0.000, p = 0.01), respectively. Tegner was significant between baseline and 48 months only for MACI (p < 0.008) compared with MF (p = 0.25). No significant difference was observed between groups for any score at 3, 12, 24, and 48-months (p > 0.05). T2-mapping values improved significantly over time in MACI compared with MF at 24 months (39.35 vs. 50.44, p = 0.007) and 48 months (36.54 vs. 48.37, p = 0.005). When comparing control values to MACI at 12-m (p = 0.714), 24-m (p = 0.175), and 48-m (p = 0.097), no significant difference was found. MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score comparison gave no statistical difference between groups. CONCLUSIONS: Clinically both techniques improved significantly over time. However, quantitative assessment showed that only newly formed tissue with MACI technique improves significantly since 12-months and maintains stable values compared with native cartilage until 48-month follow-up. MF results were never comparable to those native values. Level of evidence II.

Anatomic Risk Factors for Focal Cartilage Lesions in the Patella and Trochlea: A Case-Control Study.

BACKGROUND: Focal cartilage lesions in the patellofemoral (PF) joint are common. Several studies correlated PF risk factors with PF instability, anterior knee pain, and PF arthritis; however, there is a lack of evidence correlating those factors to PF focal cartilage lesions. PURPOSE: To evaluate the influence of the anatomic PF risk factors in patients with isolated focal PF cartilage lesions. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Patients with isolated PF focal cartilage lesions were included in the cartilage lesion group, and patients with other pathologies and normal PF cartilage were included in the control group. Multiple PF risk factors were accessed on magnetic resonance imaging scans: patellar morphology (patellar width, patellar thickness, and patellar angle), trochlear morphology (trochlear sulcus angle, lateral condyle index, and trochlear sulcus depth), patellar height (Insall-Salvati ratio and Caton-Deschamps index), axial patellar positioning (patellar tilt, angle of Fulkerson), and quadriceps vector (tibial tuberosity-trochlear groove distance). RESULTS: A total of 135 patients were included in the cartilage lesion group and 100 in the control group. As compared with the control group, the cartilage lesion group had a higher sulcus angle (P = .0007), lower trochlear sulcus depth (P < .0001), lower angle of Fulkerson (P < .0001), lower patellar width (P = .0003), and higher Insall-Salvati ratio (P < .0001). From the patients in the cartilage lesion group, 36% had trochlear dysplasia; 27.6%, patella alta; and 24.7%, abnormal patellar tilt. These parameters were more frequent in the cartilage lesion group (P < .0001). Trochlear lesions were more frequent in men, presented at an older age, and had fewer associated anatomic risk factors. Patellar lesions, conversely, were more frequent in women, presented at younger age, and were more closely associated with anatomic risk factors. CONCLUSION: PF anatomic abnormalities are significantly more common in patients with full-thickness PF cartilage lesions. Trochlear dysplasia, patella alta, and excessive lateral patellar tilt are the most common correlated factors, especially in patellar lesions.

Is Patient Satisfaction Associated With Clinical Outcomes After Osteochondral Allograft Transplantation in the Knee?

BACKGROUND: The association between patient satisfaction and patient-reported outcomes after cartilage repair is not well understood. PURPOSE: To investigate the association of patient satisfaction with pain, function, activity level, and quality of life after fresh osteochondral allograft (OCA) transplantation in the knee. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: This study comprised 371 patients (396 knees) who underwent primary OCA transplantation for osteochondral lesions in the knee between 1997 and 2015. Mean ± SD patient age was 31.8 ± 11.6 years, and 62% were male. The majority of grafts (62%) were located on the femoral condyle; the mean number of grafts per knee was 1.5 ± 0.8; and the median graft area was 6.9 cm2 (range, 1.8-50 cm2). Pain, function, activity level, and quality of life were evaluated pre- and postoperatively via International Knee Documentation Committee scores and Knee injury and Osteoarthritis Outcome Scores. Patient satisfaction with the results of the OCA transplantation was assessed postoperatively. All follow-up evaluations occurring at postoperative 1 year or later were included in the analysis. RESULTS: The mean follow-up time was 5.5 years. Overall, the satisfaction rate was 88.1%, and this rate was constant over time. Satisfaction rates varied by diagnosis, age, sex, and anatomic location of the allograft. Postoperative International Knee Documentation Committee pain, function, and total scores differed between patients who were satisfied and not satisfied (all P < .001). All Knee injury and Osteoarthritis Outcome Score subscale results differed between those who were satisfied and not satisfied (all P < .001). Having a diagnosis of osteochondritis dissecans was the only variable that predicted which patients would be satisfied with the results of the allograft, after controlling for age, sex, anatomic location of the graft, and number of grafts. CONCLUSION: A consistently high and durable patient satisfaction rate after OCA transplantation was found. Satisfied patients reported lower pain and higher function, activity levels, and quality of life as compared with patients who were not satisfied. Patients with osteochondritis dissecans had a particularly high level of satisfaction with the OCA procedure.

Micromass cultures are effective for differentiation of human amniotic fluid stem cells into chondrocytes

OBJECTIVES: Articular cartilage is vulnerable to injuries and undergoes an irreversible degenerative process. The use of amniotic fluid mesenchymal stromal stem cells for the reconstruction of articular cartilage is a promising therapeutic alternative. The aim of this study was to investigate the chondrogenic potential of amniotic fluid mesenchymal stromal stem cells from human amniotic fluid from second trimester pregnant women in a micromass system (high-density cell culture) with TGF-β3 for 21 days. METHODS: Micromass was performed using amniotic fluid mesenchymal stromal stem cells previously cultured in a monolayer. Chondrocytes from adult human normal cartilage were used as controls. After 21 days, chondrogenic potential was determined by measuring the expression of genes, such as SOX-9, type II collagen and aggrecan, in newly differentiated cells by real-time PCR (qRT-PCR). The production of type II collagen protein was observed by western blotting. Immunohistochemistry analysis was also performed to detect collagen type II and aggrecan. This study was approved by the local ethics committee. RESULTS: SOX-9, aggrecan and type II collagen were expressed in newly differentiated chondrocytes. The expression of SOX-9 was significantly higher in newly differentiated chondrocytes than in adult cartilage. Collagen type II protein was also detected. CONCLUSION: We demonstrate that stem cells from human amniotic fluid are a suitable source for chondrogenesis when cultured in a micromass system. amniotic fluid mesenchymal stromal stem cells are an extremely viable source for clinical applications, and our results suggest the possibility of using human amniotic fluid as a source of mesenchymal stem cells.

Natural Type II Collagen Hydrogel, Fibrin Sealant, and Adipose-Derived Stem Cells as a Promising Combination for Articular Cartilage Repair.

Objective Articular cartilage is an avascular tissue with limited ability of self-regeneration and the current clinical treatments have restricted capacity to restore damages induced by trauma or diseases. Therefore, new techniques are being tested for cartilage repair, using scaffolds and/or stem cells. Although type II collagen hydrogel, fibrin sealant, and adipose-derived stem cells (ASCs) represent suitable alternatives for cartilage formation, their combination has not yet been investigated in vivo for focal articular cartilage defects. We performed a simple experimental procedure using the combination of these 3 compounds on cartilage lesions of rabbit knees. Design The hydrogel was developed in house and was first tested in vitro for chondrogenic differentiation. Next, implants were performed in chondral defects with or without ASCs and the degree of regeneration was macroscopically and microscopically evaluated. Results Production of proteoglycans and the increased expression of collagen type II (COL2α1), aggrecan (ACAN), and sex-determining region Y-box 9 (SOX9) confirmed the chondrogenic character of ASCs in the hydrogel in vitro. Importantly, the addition of ASC induced a higher overall repair of the chondral lesions and a better cellular organization and collagen fiber alignment compared with the same treatment without ASCs. This regenerating tissue also presented the expression of cartilage glycosaminoglycan and type II collagen. Conclusions Our results indicate that the combination of the 3 compounds is effective for articular cartilage repair and may be of future clinical interest.

Co-culture of dedifferentiated and primary human chondrocytes obtained from cadaveric donor enhance the histological quality of repair tissue: an in-vivo animal study.

To compare the quality of the repair tissue in three-dimensional co-culture of human chondrocytes implanted in an in vivo model. Six cadaveric and five live human donors were included. Osteochondral biopsies from the donor knees were harvested for chondrocyte isolation. Fifty percent of cadaveric chondrocytes were expanded until passage-2 (P2) while the remaining cells were cryopreserved in passage-0 (P0). Fresh primary chondrocytes (P0f) obtained from live human donors were co-cultured. Three-dimensional constructs were prepared with a monolayer of passage-2 chondrocytes, collagen membrane (Geistlich Bio-Gide®), and pellet of non-co-cultured (P2) or co-cultured chondrocytes (P2 + P0c, P2 + P0f). Constructs were implanted in the subcutaneous tissue of athymic mice and left for 3 months growth. Safranin-O and Alcian blue staining were used to glycosaminoglycan content assessment. Aggrecan and type-II collagen were evaluated by immunohistochemistry. New-formed tissue quality was evaluated with an adaptation of the modified O'Driscoll score. Histological quality of non-co-cultured group was 4.37 (SD ±4.71), while co-cultured groups had a mean score of 8.71 (SD ±3.98) for the fresh primary chondrocytes and 9.57 (SD ±1.27) in the cryopreserved chondrocytes. In immunohistochemistry, Co-culture groups were strongly stained for type-II and aggrecan not seen in the non-co-cultured group. It is possible to isolate viable chondrocytes from cadaveric human donors in samples processed in the first 48-h of dead. There is non-significant difference between the numbers of chondrocytes isolated from live or cadaveric donors. Cryopreservation of cadaveric primary chondrocytes does not alter the capability to form cartilage like tissue. Co-culture of primary and passaged chondrocytes enhances the histological quality of new-formed tissue compared to non-co-cultured cells.

A retinaculum-sparing surgical approach preserves porcine stifle joint cartilage in an experimental animal model of cartilage repair.

BACKGROUND: This study compares a traditional parapatellar retinaculum-sacrificing arthrotomy to a retinaculum-sparing arthrotomy in a porcine stifle joint as a cartilage repair model. FINDINGS: Surgical exposure of the femoral trochlea of ten Yucatan pigs stifle joint was performed using either a traditional medial parapatellar approach with retinaculum incision and luxation of the patella (n = 5) or a minimally invasive (MIS) approach which spared the patellar retinaculum (n = 5). Both classical and MIS approaches provided adequate access to the trochlea, enabling the creation of cartilage defects without difficulties. Four full thickness, 4 mm circular full-thickness cartilage defects were created in each trochlea. There were no intraoperative complications observed in either surgical approach. All pigs were allowed full weight-bearing and full range of motion immediately postoperatively and were euthanized between 2 and 3 weeks. The traditional approach was associated with increased cartilage wear compared to the MIS approach. Two blinded raters performed gross evaluation of the trochlea cartilage surrounding the defects according to the modified ICRS cartilage injury classification. The traditional approach cartilage received a significantly worse score than the MIS approach group from both scorers (3.2 vs 0.8, p = 0.01 and 2.8 vs 0, p = 0.005 respectively). CONCLUSION: The MIS approach results in less damage to the trochlear cartilage and faster return to load bearing activities. As an arthrotomy approach in the porcine model, MIS is superior to the traditional approach.

Development of a Fresh Osteochondral Allograft Program Outside North America.

OBJECTIVE: To standardize and to develop a fresh osteochondral allograft protocol of procurement, processing and surgical utilization in Brazil. This study describes the steps recommended to make fresh osteochondral allografts a viable treatment option in a country without previous fresh allograft availability. DESIGN: The process involves regulatory process modification, developing and establishing procurement, and processing and surgical protocols. RESULTS: Legislation: Fresh osteochondral allografts were not feasible in Brazil until 2009 because the law prohibited preservation of fresh grafts at tissue banks. We approved an amendment that made it legal to preserve fresh grafts for 30 days from 2°C to 6°C in tissue banks. Procurement: We changed the protocol of procurement to decrease tissue contamination. All tissues were procured in an operating room. Processing: Processing of the grafts took place within 12 hours of tissue recovery. A serum-free culture media with antibiotics was developed to store the grafts. Surgeries: We have performed 8 fresh osteochondral allografts on 8 knees obtaining grafts from 5 donors. Mean preoperative International Knee Documentation Committee (IKDC) score was 31.99 ± 13.4, improving to 81.26 ± 14.7 at an average of 24 months' follow-up. Preoperative Knee Injury and Oseoarthritis Outcome Score (KOOS) score was 46.8 ± 20.9 and rose to 85.24 ± 13.9 after 24 months. Mean preoperative Merle D'Aubigne-Postel score was 8.75 ± 2.25 rising to 16.1 ± 2.59 at 24 months' follow-up. CONCLUSION: To our knowledge, this is the first report of fresh osteochondral allograft transplantation in South America. We believe that this experience may be of value for physicians in countries that are trying to establish an osteochondral allograft transplant program.

Platelet-rich plasma releasate differently stimulates cellular commitment toward the chondrogenic lineage according to concentration.

Platelet-rich plasma has been used to treat articular cartilage defects, with the expectations of anabolic and anti-inflammatory effects. However, its role on cellular chondrogenic or fibrogenic commitment is still a controversy. Herein, the role of platelet-rich plasma releasate, the product obtained following platelet-rich plasma activation, on cellular commitment toward the chondrogenic lineage was evaluated in vitro. Human nasoseptal chondrogenic cells and human bone marrow mesenchymal stromal cells were used as cell types already committed to the chondrogenic lineage and undifferentiated cells, respectively, as different concentrations of platelet-rich plasma releasate were tested in comparison to commonly used fetal bovine serum. Low concentration of platelet-rich plasma releasate (2.5%) presented similar effects on cellular growth compared to 10% fetal bovine serum, for both cell types. In a three-dimensional culture system, platelet-rich plasma releasate alone did not induce full nasoseptal chondrogenic cells cartilage-like pellet formation. Nonetheless, platelet-rich plasma releasate played a significant role on cell commitment as high-passage nasoseptal chondrogenic cells only originated cartilage-like pellets when expanded in the presence of platelet-rich plasma releasate rather than fetal bovine serum. Histological analyses and measurements of pellet area demonstrated that even low concentrations of platelet-rich plasma releasate were enough to prevent nasoseptal chondrogenic cells from losing their chondrogenic potential due to in vitro expansion thereby promoting their recommitment. Low concentration of platelet-rich plasma releasate supplemented in chondrogenic medium also increased the chondrogenic potential of mesenchymal stromal cells seeded on collagen-hyaluronic acid scaffolds, as observed by an increase in chondrogenic-related gene expression, sulfated glycosaminoglycan production, and compressive modulus following in vitro culture. On the contrary, higher concentration of platelet-rich plasma releasate (10%) hampered some of these features. In conclusion, platelet-rich plasma releasate was able to prevent cellular chondrogenic capacity loss, inducing regain of their phenotype, and modulate cell commitment. Our data support the hypothesis of platelet-rich plasma chondrogenic potential, allowing fetal bovine serum substitution for platelet-rich plasma releasate at specific concentrations in culture medium when chondrogenic commitment is desired on specific cell types and moments of culture.

Osteochondral Allograft Transplantation for Knee Lesions after Failure of Cartilage Repair Surgery.

OBJECTIVE: The objective of this study was to assess the outcome of osteochondral allograft (OCA) transplantation as a salvage procedure after various cartilage repair surgeries. DESIGN: One hundred sixty-four knees in 163 patients (mean age = 32.6 years; range = 11-59 years; 55% males) were treated with OCA transplantation after subchondral marrow stimulation (SMS), osteochondral autograft transplantation (OAT), and autologous chondrocyte implantation (ACI). The majority of previous procedures were isolated SMS in 145 knees (88.4%). Mean allograft size was 8.5 ± 7.9 cm(2). The most common location was in femoral condyle. The number and type of reoperations on the operative knee were assessed. Failure of the OCA transplantation was defined as any reoperation resulting in removal of the allograft. Functional outcomes were evaluated. RESULTS: Sixty-eight knees had reoperations after OCA transplantation. Thirty-one knees (18.9%) were classified as allograft failures. The median time to failure was 2.6 ± 6.8 years (range = 0.7-23.4 years). Survivorship of the graft was 82% at 10 years and 74.9% at 15 years. Patients whose grafts were still in situ had a mean of 8.5 ± 5.6 years of follow-up. Scores on all functional outcomes scales improved significantly from preoperatively to latest follow-up. Eighty-nine percent of OCA transplantation patients reported being "extremely satisfied" or "satisfied." CONCLUSION: Despite the high reoperation rate, OCA transplantation is a successful salvage surgical treatment after cartilage repair procedures. This cohort showed improved survivorship and functional outcomes of OCA transplantation after SMS, ACI, and OAT.

Fresh osteochondral allografts in the knee: comparison of primary transplantation versus transplantation after failure of previous subchondral marrow stimulation.

BACKGROUND: In most treatment algorithms, osteochondral allograft (OCA) transplantation is regarded as an alternative salvage procedure when other, previous reparative treatments have failed. PURPOSE: To compare the outcomes of a retrospective matched-pair cohort of (1) primary OCA transplantation and (2) OCA transplantation after failure of previous subchondral marrow stimulation. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: An OCA database was used to identify 46 knees that had OCA transplantation performed as a primary treatment (group 1) and 46 knees that underwent OCA transplantation after failure of previous subchondral marrow stimulation (group 2). All patients had a minimum of 2 years' follow-up. Patients in each group were matched for age (±5 years), diagnosis (osteochondral lesion, degenerative chondral lesion, traumatic chondral injury), and graft size (small, <5 cm2; medium, 5-10 cm2; large, >10 cm2). The groups had similar body mass indexes, sex distributions, and graft locations (femoral condyle, patella, and trochlea. The number and type of further surgeries after the OCA transplantation were assessed; failure was defined as any reoperation resulting in removal of the graft. Functional outcomes were evaluated by use of the modified Merle d'Aubigné-Postel (18-point) scale, International Knee Documentation Committee (IKDC) subjective knee evaluation form, Knee injury and Osteoarthritis Outcomes Score (KOOS), and the Knee Society function (KS-F) scale. Patient satisfaction, according to a 5-point scale from "extremely satisfied" to "dissatisfied," was recorded at the latest follow-up. RESULTS: Eleven of 46 knees (24%) in group 1 had reoperations, compared with 20 of 46 knees (44%) in group 2 (P = .04). The OCA was classified as a failure in 5 knees (11%) in group 1 and 7 knees (15%) in group 2 (P = .53). At 10 years of follow-up, survivorship of the graft was 87.4% and 86% in groups 1 and 2, respectively. Both groups showed improvement in pain and function on all subjective scores from preoperatively to the latest follow-up (all P < .001). Results showed that 87% of patients in group 1 and 97% in group 2 were "satisfied" or "extremely satisfied" with the OCA transplantation. CONCLUSION: Favorable results were shown in both groups with significant improvement of functional scores and excellent survivorship. Despite the higher reoperation rate in the previously treated group, previous subchondral marrow stimulation did not adversely affect the survivorship and functional outcome of OCA transplantation.