Successful Autologous Stem Cell Transplant After 21 Years of Cryopreservation.
Authors: Cherry Mohamad Ali , Kern William , Wagenman Benjamin , Epstein Robert B. , Kratochvil Kris , Selby George B. , Holter Jennifer 
Published: October 2019

Abstract
Abstract 4603

Introduction:
Successful transplantation of cryopreserved hematopoietic stem cell (HSC) can be regularly achieved provided sufficient numbers of cells are administered. However the optimal conditions for preparation, freezing and thawing remain to be defined. The duration of hematopoietic stem cell viability is unclear. The ultimate measure of viability has remained in vivo hematologic recovery following transplantation. Evidence of autologous repopulation in preclinical setting has been seen at 14 years after bone marrow transplant and after 12 years in the clinical setting after peripheral stem cell transplant. We report a successful transplantation in a patient in whom autologous cryopreserved marrow with cellular dose of 1.21 × 108/kg was infused 21 years following collection.

Case:
The patient is 43 year old man found to have follicular lymphoma with bone marrow involvement in 1989 at age 22. He achieved complete remission after treatment with two cycles of Chorambucil. Bone marrow procurement and cryopreservation was performed at that time for possible subsequent infusion. The procured marrow consisted of a total cell count of 1.21 × 10^8 cells/per kg body wt with a total volume of 354 ml. Equal parts of 20% DMSO were combined with marrow to a final concentration of 10% DMSO. The marrow was then stored in the liquid phase of nitrogen from date of collection until date of infusion 21 years later. Our patient relapsed in 1996, and eventually underwent treatment in 2006 with six cycles of Fludarabine and Rituximab, achieving a complete remission. He continued Rituximab therapy maintenance every 6 months for a total of 2 years. During Rituximab therapy, he was noted to have pancytopenia Work-up confirmed MDS with 5q- and translocation of long arm of chromosome 6q21 and short arm 17p13 in 20/20 cells by karyotype analysis. Patient elected to proceed with the cryopreserved marrow transplant. Assessment of cryopreserved marrow for dysplasia was undertaken showing no evidence of cytogenetic or histological changes. The patient was prepared with Busulfan IV at 0.8/kg q 6 hours × 4 days and Cyclophosphamide 60mg/kg IV × 2 days. The marrow was infused 21 years following its procurement. Samples from the infused marrow showed 65–75% viability by Tryptan blue assay. White cell engraftment occurred on day 17 and platelet reached 20,000 by day 30.
Follow-up 2 months post transplant revealed persistent mild pancytopenia, WBC of 2.6 with ANC 1500, Hgb 9.8 and platelets of 43,000. FISH analysis for 5q performed showed 85/200 cells positive for 5q-. Bone marrow biopsy confirmed dysplastic features consistent with his pre-transplant bone marrow biopsy.
Our case illustrates that even in the setting of marginal numbers of infused marrow components and after prolonged cryopreservation, repopulation can readily occur. However, inability to eliminate the malignant clone following stable engraftment brings to light both the necessity of adequate ablation in pretransplant conditioning, and the importance of graft-versus-tumor effect in marrow born malignancies. To our knowledge, this is the oldest successful cryopreserved autologous bone transplant at 21 years post preservation. As novel uses of stem cells advance, optimal storage of various cellular components is necessary. This should be further investigated on a larger scale in the future.

Disclosures:
No relevant conflicts of interest to declare.