Effectiveness of Clinical-Grade Chondroitin Sulfate and Ascorbic Acid in Mitigating Cryoprotectant Toxicity in Porcine Articular Cartilage

The Low Survivability of Transplanted Gonadal Grafts: The Impact of Cryopreservation and Transplantation Conditions on Mitochondrial Function

Advances in tissue preservation techniques have allowed reproductive medicine and assisted reproductive technologies (ARTs) to flourish in recent years. Because radio- and chemotherapy procedures are often gonadotoxic, irreversible damage can preclude future gamete production and endocrine support. Accordingly, in recent years, the freezing and storage of gonadal tissue fragments prior to the first oncological treatment appointment and autologous transplantation post-recovery have been considered improved solutions for fertility recovery in cancer survivors. Nevertheless, the cryopreservation and transplantation of thawed tissues is still very limited, and positive outcomes are relatively low. This review aims to discuss the limitations of oncofertility protocols with a focus on the impacts of mitochondrial dysfunction, oxidative stress, and the loss of antioxidant defense in graft integrity.

Chondrocyte Viability of Particulated Porcine Articular Cartilage Is Maintained in Tissue Storage After Cryoprotectant Exposure, Vitrification, and Tissue Warming

OBJECTIVE

Vitrification of articular cartilage (AC) is a promising technique which may enable long-term tissue banking of AC allografts. We previously developed a 2-step, dual-temperature, multi-cryoprotectant agent (CPA) loading protocol to cryopreserve particulated AC (1 mm3 cubes). Furthermore, we also determined that the inclusion of ascorbic acid (AA) effectively mitigates CPA toxicity in cryopreserved AC. Prior to clinical translation, chondrocytes must remain viable after tissue re-warming and before transplantation. However, the effects of short-term hypothermic storage of particulated AC after vitrification and re-warming are not documented. This study evaluated the chondrocyte viability of post-vitrified particulated AC during a 7-day tissue storage period at 4 °C. We hypothesized that porcine particulated AC could be stored for up to 7 days after successful vitrification without significant loss of cell viability, and these results would be enhanced when cartilage is incubated in storage medium supplemented with clinical grade AA.

DESIGN

Three experimental groups were examined at 5 time points: a fresh control (only incubated in medium), a vitrified - AA group, and a vitrified + AA group (N = 7).

RESULTS

There was a mild decline in cell viability but both treatment groups maintained a viability of greater than 80% viable cells which is acceptable for clinical translation.

CONCLUSION

We determined that particulated AC can be stored for up to 7 days after successful vitrification without a clinically significant decline in chondrocyte viability. This information can be used to guide tissue banks regarding the implementation of AC vitrification to increase cartilage allograft availability.

Nanowarming and ice-free cryopreservation of large sized, intact porcine articular cartilage

Successful organ or tissue long-term preservation would revolutionize biomedicine. Cartilage cryopreservation enables prolonged shelf life of articular cartilage, posing the prospect to broaden the implementation of promising osteochondral allograft (OCA) transplantation for cartilage repair. However, cryopreserved large sized cartilage cannot be successfully warmed with the conventional convection warming approach due to its limited warming rate, blocking its clinical potential. Here, we develope a nanowarming and ice-free cryopreservation method for large sized, intact articular cartilage preservation. Our method achieves a heating rate of 76.8 °C min-1, over one order of magnitude higher than convection warming (4.8 °C min-1). Using systematic cell and tissue level tests, we demonstrate the superior performance of our method in preserving large cartilage. A depth-dependent preservation manner is also observed and recapitulated through magnetic resonance imaging and computational modeling. Finally, we show that the delivery of nanoparticles to the OCA bone side could be a feasible direction for further optimization of our method. This study pioneers the application of nanowarming and ice-free cryopreservation for large articular cartilage and provides valuable insights for future technique development, paving the way for clinical applications of cryopreserved cartilage.