Cartilage allograft techniques and materials

Subcutaneously Transplanted Fresh Cartilage in Allogeneic and Xenogeneic Immunocompetent Mouse

Cartilage is considered to be immune privileged in general. Clinically, live cells are removed from subcutaneously transplanted allogeneic cartilage mainly for preservation and for infection control. However, because maintaining cartilage feature requires live chondrocyte, it would be beneficial to subcutaneously transplant cartilage with live chondrocyte even if it was allogeneic. We harvested femoral head from 3-week-old male C57BL/6 mice, subcutaneously transplanted to 6-week-old male mice, BALB/c, BALB/c nu/nu, or C57BL/6-Tg (enhanced green fluorescent protein [EGFP] under the control of the CMV-IE enhancer, chicken beta-actin promoter, rabbit beta-globin genomic DNA [CAG promoter]), as allogeneic, allogeneic immunodeficient control, or syngeneic transplantation. We also transplanted cartilaginous particles from human induced pluripotent stem cells derived from human leukocyte antigen homozygous donor to 6-week-old male mice either BALB/c and BALB/c nu/nu as xenogeneic or xenogeneic immunodeficient control. The transplantation periods were 1, 2, 3, 4, 8, 12, and 24 weeks. As the result, we did not observe exposure of the transplant or apparent macroscopic inflammatory in all samples. Histological analysis suggested that the femoral head showed focal ossification and thinning in syngeneic transplantation. In allogeneic transplantation, slight invasion of CD3 (+) T cell and the denaturation of the cartilage were observed, suggesting immune reaction against allogeneic cartilage. In xenogeneic transplantation, slight invasion of CD3 (+) cell and CD4 (+) cell and the structure of the perichondrium-like tissue got unclear, suggesting slight immune reaction against xenogeneic cartilage. Our findings suggest that we should carefully investigate for appropriate procedure to control immune reaction against allogeneic cartilage with live chondrocyte and to maintain its cartilage feature for long time.

Simultaneous Treatment of Osteochondral Lesion Does Not Affect the Mid- to Long-Term Outcomes of Ligament Repair for Acute Ankle Sprain: A Retrospective Comparative Study with a 3–11-Year Follow-up

Purpose

This study aims to evaluate the mid- to long-term outcome of concurrent arthroscopic treatment of osteochondral lesion (OCL) and open anatomical repair of lateral ankle ligaments for severe acute ankle sprain patients and compare them to the outcome of those without OCL.

Methods

A total of 166 patients with grade III acute lateral ankle ligament injuries underwent concurrent ankle arthroscopy and open anatomic ligament repair. Forty-three patients (group A) with OCL underwent arthroscopic treatment followed by open ligament repair. A total of 105 patients (group B) without OCL were followed up as the control. The evaluation parameters included sports recovery, postoperative visual analog scale (VAS) pain score, American Orthopaedic Foot and Ankle Society (AOFAS) score, Tegner score, sprain recurrence, satisfaction, and range of motion. Patients in group A were then subgroup-analyzed according to age, sex, body mass index, injury side, OCL location, and stage (Ferkel and Cheng’s staging system).

Results

The postoperative exercise level of the two groups recovered to more than 90% of the normal level (91.2% ± 11.2% in group A and 90.9% ± 13.3% in group B, n.s.). The average time of group A and group B to return to preinjury sports activity was respectively 4.4 ± 1.0 months and 4.4 ± 1.2 months with no significant difference (p = 0.716). No significant differences were found in the preoperation VAS pain score, AOFAS score, and Tegner score between the two groups. The postoperative VAS pain score in group A was significantly higher than that in group B (0.8 ± 1.7 vs. 0.3 ± 0.8, p = 0.027), but the difference was not clinically important. The postoperative VAS pain score of patients with stage D–F lesions was significantly higher than that of patients with stage B–C lesions (1.3 ± 2.1 vs. 0.3 ± 0.9, p = 0.038).

Conclusions

For the severe acute ankle sprain combined with OCL, the simultaneous arthroscopic treatment and open lateral ankle ligament repair achieved good mid- to long-term outcomes. Except that the pain was more pronounced than in the control group, there were no differences in other outcomes. Postoperative pain was positively correlated with the grade of OCL.

Autologous costal chondral transplantation and costa-derived chondrocyte implantation: emerging surgical techniques

It is a great challenge to cure symptomatic lesions and considerable defects of hyaline cartilage due to its complex structure and poor self-repair capacity. If left untreated, unmatured degeneration will cause significant complications. Surgical intervention to repair cartilage may prevent progressive joint degeneration. A series of surgical techniques, including biological augmentation, microfracture and bone marrow stimulation, autologous chondrocyte implantation (ACI), and allogenic and autogenic chondral/osteochondral transplantation, have been used for various indications. However, the limited repairing capacity and the potential pitfalls of these techniques cannot be ignored. Increasing evidence has shown promising outcomes from ACI and cartilage transplantation. Nevertheless, the morbidity of autologous donor sites and limited resource of allogeneic bone have considerably restricted the wide application of these surgical techniques. Costal cartilage, which preserves permanent chondrocytes and the natural osteochondral junction, is an ideal candidate for the restoration of cartilage defects. Several in vitro and in vivo studies have shown good performance of costal cartilage transplantation. Although costal cartilage is a classic donor in plastic and cosmetic surgery, it is rarely used in skeletal cartilage restoration. In this review, we introduce the fundamental properties of costal cartilage and summarize costa-derived chondrocyte implantation and costal chondral/osteochondral transplantation. We will also discuss the pitfalls and pearls of costal cartilage transplantation. Costal chondral/osteochondral transplantation and costa-based chondrocytotherapy might be up-and-coming surgical techniques for recalcitrant cartilage lesions.

Stem Cells for Cartilage Repair: Preclinical Studies and Insights in Translational Animal Models and Outcome Measures

Due to the restricted intrinsic capacity of resident chondrocytes to regenerate the lost cartilage postinjury, stem cell-based therapies have been proposed as a novel therapeutic approach for cartilage repair. Moreover, stem cell-based therapies using mesenchymal stem cells (MSCs) or induced pluripotent stem cells (iPSCs) have been used successfully in preclinical and clinical settings. Despite these promising reports, the exact mechanisms underlying stem cell-mediated cartilage repair remain uncertain. Stem cells can contribute to cartilage repair via chondrogenic differentiation, via immunomodulation, or by the production of paracrine factors and extracellular vesicles. But before novel cell-based therapies for cartilage repair can be introduced into the clinic, rigorous testing in preclinical animal models is required. Preclinical models used in regenerative cartilage studies include murine, lapine, caprine, ovine, porcine, canine, and equine models, each associated with its specific advantages and limitations. This review presents a summary of recent in vitro data and from in vivo preclinical studies justifying the use of MSCs and iPSCs in cartilage tissue engineering. Moreover, the advantages and disadvantages of utilizing small and large animals will be discussed, while also describing suitable outcome measures for evaluating cartilage repair.