HUMAN UMBILICAL CORD-DERIVED MESENCHYMAL STEM CELLS OR MICROFRACTURES ASSOCIATED TO A COLLAGEN MATRIX FOR BILATERAL KNEE CHONDRAL LESIONS REPAIR: A CLINICAL COMPARATIVE STUDY

Backgroud Collagen matrix associated to microfractures is a recognized option for chondral lesions repair. However, microfractures damage the subchondral bone and recruit an undefined amount of cells, what can lead to poor quality tissue repair. Allogenic human umbilical cord-derived mesenchymal stem cells (HUC-MSC) showed ease to obtaining, inflammatory response control, no ethic issue, no immune response. These cells can be stored in large and defined amount and be available for one-step surgery, what could improve chondral repair when associated to collagen matrix. This study aimed to compare short-term outcomes of using HUC-MSC or microfractures associated to a collagen matrix for bilateral knee chondral lesions repair. Methods The study was approved by CONEP: 1.695.843 / CAEE: 56776716.1.1001.0020. In a prospective study, three patients (mean age of 40,6 years) with bilateral knee full-thickness chondral lesions were evaluated. As the study group (SG), the right knees were treated by collagen matrix plus HUC-MSC. As the control group (CG), the left knees were treated by collagen matrix plus microfractures. Chondral defects were located in the patella (2) and the trochlea (1), and mean size was 4,6 cm2 in the SG and 3,3 cm2 in the CG. All the HUC-MSC were obtained from donors with negative serology to infections. After in vitro expansion, the HUC-MSC had 97% viability; showed negative culture bacterial and/or fungi growth, absence of mycoplasma and endotoxins; flow cytometry analysis showed positive to CD90, CD105, CD29 and CD73 and negative to CD45, CD34, CD14, CD19 and HLA-DR and normal karyotype by GTG cytogenetic analysis. By knee arthrotomy, collagen matrix Chondro-Gide was implanted on the chondral defect on both groups. SG was associated to the injection of 40 × 106 of HUC-MSC. In the CG, microfractures were performed before matrix implantation. KOOS, VAS and MRI results were compared pre and postoperatively. Results After 12 months of follow-up, KOOS and VAS scores were improved postoperatively in both groups as compared to a baseline. On the SG, all MRI showed signs of full-filling, smooth surface, complete integration to adjacent cartilage, and no bone edema. MRI showed the same findings on the CG, except one, and two knees showed bone edema. No adverse effects, rejection or complications were noted in both groups. Conclusion HUC-MSC associated to collagen matrix is a safe one-step procedure for knee chondral lesions repair and shows good outcomes when compared to collagen matrix plus microfractures in the short-term.