Is there a scientific basis for a recommended standardization of collection and cryopreservation of peripheral blood stem cell grafts?

The Effect of Donor Graft Cryopreservation on Allogeneic Hematopoietic Cell Transplantation Outcomes: A Center for International Blood and Marrow Transplant Research Analysis. Implications during the COVID-19 Pandemic

The COVID-19 pandemic has resulted in the increased use of cryopreserved grafts for allogeneic hematopoietic cell transplantation (HCT). However, information about the effect of cryopreservation on outcomes for patients receiving allogeneic donor grafts is limited. We evaluated outcomes of HCT recipients who received either fresh or cryopreserved allogeneic bone marrow (BM) or peripheral blood stem cell (PBSC) grafts reported to the Center for International Blood and Marrow Transplant Research. A total of 7397 patients were included in the analysis. Recipients of cryopreserved graft were divided into 3 cohorts based on graft source: HLA-matched related PBSC donors (n = 1051), matched unrelated PBSC donors (n = 678), and matched related or unrelated BM donors (n = 154). These patients were propensity score matched with 5514 patients who received fresh allografts. The primary endpoint was engraftment. Multivariate analyses showed no significant increased risk of delayed engraftment, relapse, nonrelapse mortality (NRM), or survival with cryopreservation of BM grafts. In contrast, cryopreservation of related donor PBSC grafts was associated with decreased platelet recovery (hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.68 to 0.78; P < .001) and an increased risk of grade II-IV (HR, 1.27; 95% CI, 1.09 to 1.48; P = .002) and grade III-IV (HR, 1.48; 95% CI, 1.19 to 1.84; P < .001) acute graft-versus-host disease. Cryopreservation of unrelated PBSC grafts was associated with delayed engraftment of neutrophils (HR, 0.77; 95% CI, 0.71 to 0.84; P < .001) and platelets (HR, 0.61; 95% CI, 0.56 to 0.66; P < .001) as well as an increased risk of NRM (HR, 1.4; 95% CI, 1.18 to 1.66; P < .001) and relapse (HR, 1.32; 95% CI, 1.11 to 1.58; P = .002) and decreased progression-free survival (HR, 1.36; 95% CI, 1.20 to 1.55; P < .001) and overall survival (OS) (HR, 1.38; 95% CI, 1.22 to 1.58; P < .001). Reasons for cryopreservation were not routinely collected; however, in a subset of unrelated donor HCT recipients, the reason was typically a change in patient condition. Products cryopreserved for patient reasons were significantly associated with inferior OS in multivariate analysis (HR, 0.65; 95% CI, 0.44 to 0.96; P = .029). We conclude that cryopreservation is associated with slower engraftment of PBSC grafts, which may be associated with inferior transplantation outcomes in some patient populations. However, the small numbers in the cryopreserved BM cohort and the lack of information on the reason for cryopreservation in all patients suggests that these data should be interpreted with caution, particularly in the context of the risks associated with unexpected loss of a graft during the pandemic. Future analyses addressing outcomes when cryopreservation is universally applied are urgently required.

Adverse events of cryopreserved hematopoietic stem cell infusions in adults: a single-center observational study

BACKGROUND

Autologous hematopoietic stem cell (HSC) transplantation has been used for almost three decades for the management of malignant hematologic diseases and some solid tumors. Dimethyl sulfoxide (DMSO) is used as a cryoprotective agent for hematopoietic progenitor cells (HPCs) collected by apheresis (HPC-A). We evaluated the factors contributing to the occurrence of adverse events (AEs) of cryopreserved HPC-A infusion.

STUDY DESIGN AND METHODS

Between January 2009 and June 2014, a total of 1269 (1191 patients) consecutive HPC-A infusions were given to adult patients undergoing autologous HSC transplantation at Barnes-Jewish Hospital. Only infusions on the first day of transplant were included in the analysis.

RESULTS

AEs were reported in 480 (37.8%) infusions. The most common AEs were facial flushing in 189 (39.4%) infusions, nausea and/or vomiting in 183 (38.1%) infusions, hypoxia requiring oxygen in 139 (29%) infusions, and chest tightness in 80 (16.7%) infusions. Multivariate analysis using logistic regression showed that female sex (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.40-2.26; p < 0.0001), diagnosis other than multiple myeloma (OR, 1.44; 95% CI, 1.12-1.84; p = 0.004), larger volume of infusion per body weight (OR, 1.66; 95% CI, 1.29-2.15; p < 0.0001), and number of granulocytes infused per body weight (OR, 1.30; 95% CI, 1.01-1.67; p = 0.042) were significant predictors of occurrence of AEs during infusion.

CONCLUSION

AEs due to HPC-A infusion occurred in more than one-third of patients. Interventions need to be instituted to reduce AEs and thus improve the safety of HPC-A infusion. Many of these toxicities can be attributed to DMSO, and this is reflected in the volume of infusion. It might be warranted to consider implementing DMSO-reducing protocols before infusion.

Cryopreservation of testicular tissue or testicular cell suspensions: a pivotal step in fertility preservation

BACKGROUND

Germ cell depletion caused by chemical or physical toxicity, disease or genetic predisposition can occur at any age. Although semen cryopreservation is the first reflex for preserving male fertility, this cannot help out prepubertal boys. Yet, these boys do have spermatogonial stem cells (SSCs) that able to produce sperm at the start of puberty, which allows them to safeguard their fertility through testicular tissue (TT) cryopreservation. SSC transplantation (SSCT), TT grafting and recent advances in in vitro spermatogenesis have opened new possibilities to restore fertility in humans. However, these techniques are still at a research stage and their efficiency depends on the amount of SSCs available for fertility restoration. Therefore, maintaining the number of SSCs is a critical step in human fertility preservation. Standardizing a successful cryopreservation method for TT and testicular cell suspensions (TCSs) is most important before any clinical application of fertility restoration could be successful.

OBJECTIVE AND RATIONALE

This review gives an overview of existing cryopreservation protocols used in different animal models and humans. Cell recovery, cell viability, tissue integrity and functional assays are taken into account. Additionally, biosafety and current perspectives in male fertility preservation are discussed.

SEARCH METHODS

An extensive PubMED and MEDline database search was conducted. Relevant studies linked to the topic were identified by the search terms: cryopreservation, male fertility preservation, (immature)testicular tissue, testicular cell suspension, spermatogonial stem cell, gonadotoxicity, radiotherapy and chemotherapy.

OUTCOMES

The feasibility of fertility restoration techniques using frozen-thawed TT and TCS has been proven in animal models. Efficient protocols for cryopreserving human TT exist and are currently applied in the clinic. For TCSs, the highest post-thaw viability reported after vitrification is 55.6 ± 23.8%. Yet, functional proof of fertility restoration in the human is lacking. In addition, few to no data are available on the safety aspects inherent to offspring generation with gametes derived from frozen-thawed TT or TCSs. Moreover, clarification is needed on whether it is better to cryopreserve TT or TCS.

WIDER IMPLICATIONS

Fertility restoration techniques are very promising and expected to be implemented in the clinic in the near future. However, inter-center variability needs to be overcome and the gametes produced for reproduction purposes need to be subjected to safety studies. With the perspective of a future clinical application, there is a dire need to optimize and standardize cryopreservation and safety testing before using frozen-thawed TT of TCSs for fertility restoration.

To freeze or not to freeze peripheral blood stem cells prior to allogeneic transplantation from matched related donors

BACKGROUND

The standard practice in allogeneic stem cell transplant (alloSCT) is to infuse peripheral blood stem cells (PBSC) the same day or the day after collection once the patient has received conditioning regimen. To obtain and freeze PBSC prior to SCT would be desirable to get a better logistic and to confirm the quality of the product. Unfortunately, studies comparing both approaches are lacking.

AIM

In this retrospective study, we analyze the impact of using fresh (N: 107) or previously frozen PBSC (N: 224) on overall outcomes among patients consecutively undergoing alloPBSCT from a matched related donor.

RESULTS

Granulocyte engraftment (>500/mcl × 3 days) was faster in the frozen group (14 vs. 16 days, respectively; P = 0.001), while no significant differences on platelet recovery were observed. Patients receiving frozen PBSC had a higher incidence of global acute graft-versus-host disease (aGVHD) (63 vs. 44%, P < 0.001) mostly involving skin and had an earlier onset (13 vs. 30 days, P < 0.001). Response to first-line treatment with corticoids was similar in both groups. No statistically significant differences were found regarding overall chronic GVHD (58 vs. 66%) nor global survival (44 vs 48%), disease-free survival (39 vs. 33%), non-relapse mortality (24 vs. 16% at 1 year), and relapse rates in the frozen vs. fresh group, respectively.

CONCLUSIONS

Infusion of previously frozen stem cells may achieve similar overall outcomes compared to fresh infusion, allowing to program donor apheresis and transplantation. However, cryopreservation might influence on the different pattern of aGVHD, issue that deserves further studies.