Cryopreservation of Growth Factor-Mobilized Peripheral Blood Stem Cells Does Not Compromise Major Outcomes after Allogeneic Hematopoietic Cell Transplantation: A Single-Center Experience

A Retrospective Analysis of Fresh versus Cryopreserved Allogenic Bone Marrow Transplant within a Pediatric Population: A Change in Practice Due to the COVID-19 Pandemic

BACKGROUND

Several adult studies show mixed reports in clinical outcomes between cryopreserved and fresh stem cell products, with majority reporting no significant differences and others report that there are differences in outcomes. There is limited literature reporting its impact on outcomes in pediatric hematopoietic cell transplantation (HSCT).

OBJECTIVE

To compare clinical outcomes between fresh vs cryopreserved stem cell treatment in pediatric HSCT.

STUDY DESIGN

A retrospective chart review was conducted on allogenic HSCT at Phoenix Children's Hospital between January 1, 2016, and March 31, 2023. The study included 181 patients, with 105 receiving fresh stem cell products and 76 receiving cryopreserved products. Clinical outcomes including, neutrophil and platelet recovery, graft versus host disease, immune reconstitution and survival outcome were compared.

RESULTS

Study subjects had median follow-up of 997 (range 12-2642) days. 92 patients were treated for a malignant disease (leukemia/lymphoma) and 89 were treated for a non-malignant disease (hemoglobinopathies, immunodeficiency/immune dysregulation, and bone marrow failure). 124 stem cell products were from bone marrow and 57 were from peripheral blood. Comparisons between fresh vs cryopreserved treatments found no significant difference in days to neutrophil engraftment (P = .47) or platelet engraftment (p=0.94). No difference in the incidence of acute graft versus host disease or chronic graft versus host disease (p = 0.70) between both groups. Immune reconstitution at 365 days post-transplant did not vary significantly between treatment groups for CD4+ T cells, CD8+ T cells, CD19+ B cells, and CD56/16+ NK cells. Overall survival at 2 years was similar in the fresh vs cryopreserved (86.7% vs 84.2%; P = .64).

CONCLUSION

These observations suggest that cryopreserved stem cell product is a reasonable alternative with comparable efficacy and potentially offering logistical advantages. Further research with larger pediatric cohorts is recommended to confirm non-inferiority of cryopreserved treatments in pediatric HSCT.

Effects, methods and limits of the cryopreservation on mesenchymal stem cells

Mesenchymal stem cells (MSCs) are a type of cell capable of regulating the immune system, as well as exhibiting self-renewal and multi-lineage differentiation potential. Mesenchymal stem cells have emerged as an essential source of seed cells for therapeutic cell therapy. It is crucial to cryopreserve MSCs in liquid nitrogen prior to clinical application while preserving their functionality. Furthermore, efficient cryopreservation greatly enhances MSCs' potential in a range of biological domains. Nevertheless, there are several limits on the MSC cryopreservation methods now in use, necessitating thorough biosafety assessments before utilizing cryopreserved MSCs. Therefore, in order to improve the effectiveness of cryopreserved MSCs in clinical stem cell treatment procedures, new technological techniques must be developed immediately. The study offers an exhaustive analysis of the state-of-the-art MSC cryopreservation techniques, their effects on MSCs, and the difficulties encountered when using cryopreserved MSCs in clinical applications.

Pros and Cons of Cryopreserving Allogeneic Stem Cell Products

The COVID-19 pandemic has precipitously changed the practice of transplanting fresh allografts. The safety measures adopted during the pandemic prompted the near-universal graft cryopreservation. However, the influence of cryopreserving allogeneic grafts on long-term transplant outcomes has emerged only in the most recent literature. In this review, the basic principles of cell cryopreservation are revised and the effects of cryopreservation on the different graft components are carefully reexamined. Finally, a literature revision on studies comparing transplant outcomes in patients receiving cryopreserved and fresh grafts is illustrated.