Comparison of stem cell viability of bone marrow cryopreserved by two different methods

Stem cells of the lower limb: Their role and potential in management of critical limb ischemia

Peripheral arterial occlusive disease (PAOD) contributes to decreased exercise tolerance, poor balance, impaired proprioception, muscle atrophy and weakness, with advanced cases resulting in critical limb ischemia (CLI) where the viability of the limb is threatened. Patients with a diagnosis of CLI have a poor life expectancy due to concomitant cardio and cerebrovascular diseases. The current treatment options to avoid major amputation by re-establishing a blood supply to the limb generally have poor outcomes. Human skeletal muscle contains both multipotent stem cells and progenitor cells and thus has a capacity for regeneration. Phase I and II studies involving transplantation of bone marrow-derived progenitor cells into CLI limbs show positive effects on wound healing and angiogenesis; the increase in quiescent satellite cell numbers observed in CLI muscle may also provide a sufficient in vivo source of resident stem cells. These indigenous cells have been shown to be capable of forming multiple mesodermal cell lineages aiding the repair and regeneration of chronically ischemic muscle. They may also serve as a repository for autologous transplantation. The behavior and responses of the stem cell population in CLI is poorly understood and this review tries to elucidate the potential of these cells and their future role in the management of CLI.

Influence of volume reduction and cryopreservation methodologies on quality of thawed umbilical cord blood units for transplantation

INTRODUCTION

Although there is considerable variability in methodology among umbilical cord blood banks, their common goal is to achieve optimal product quality for transplantation. Cryopreservation is a critical issue for a long-term maintenance of cord blood viability and colony-forming capacities.

MATERIALS AND METHODS

We designed a prospective study to compare controlled (CRF) vs. non-controlled freezing (URF) of volume-reduced cord blood units. In addition, the influence of hydroxy ethyl starch (HES) on cryopreservation was also assayed. To assess the efficiency of protocols used, cell recoveries were measured and the presence of hematopoietic colony-forming units was quantified.

RESULTS

In the study phase, we observed similar CB haematopoietc recoveries for CRF and URF strategies, except for TNC recovery that was better for HES volume reduced CB units in the URF group. When we analysed the data of routine processed CB units in samples from satellite cryovials, we found better BFU-E, CFU-GM, CFU-GEMM and CFU recoveries for those units processed with HES than without HES, in an URF manner.

CONCLUSIONS

URF of CB units is a cryopreservation procedure that allows similar hematopoietic progenitor recoveries than CRF with programmed devices. However, our study suggests that those banks that cryopreserve CB units in a URF manner should use HES for volume reduction. On the other hand, for CRF cryopreservation methodology volume reduction with and without HES are equally useful.

Viable CD34+ stem cell content of a cord blood graft: which measurement performed before transplantation is most representative?

BACKGROUND

Patient survival in allogeneic cord blood transplantation is critically dependent on total nucleated cell (TNC) count or total CD34+ cell count per kg of body weight. Theoretically, viable CD34+ cell measurement at the time of infusion should give a better indication of the suitability of a certain transplant. The relation between measurements on different samples and viable CD34+ cell count on the graft itself was analyzed.

STUDY DESIGN AND METHODS

Viable CD34+ cells were measured with a no-wash, single-platform technique with 7-aminoactinomycin D. Analysis was performed before freezing on the cord blood, after freezing and thawing on the cord blood unit itself, and on various samples.

RESULTS

Cord blood volume correlated poorly with viable CD34+ cell content (r=0.24) as did initial TNC count and WBC count (r=0.57 and r=0.48, respectively). In contrast, viable CD34 cell content determined before freezing correlated well with viable CD34 cell content of the graft (r=0.91) but was on average 25 percent higher than after freezing and thawing. The best correlations with the CD34+ cell content of the cord blood unit were obtained with CD34 cell measurements on a separate cryovial (r=0.95). These CD34 cell measurements on frozen samples were found to be very reproducible (r=0.96).

CONCLUSION

Viable CD34 cell count of the graft is both accurate and precise when measured on a separate sample frozen together with the cord blood unit. This measurement can be performed by the transplant center to exclude between-laboratory variability.

Uncontrolled-rate freezing and storage at -80 degrees C, with only 3.5-percent DMSO in cryoprotective solution for 109 autologous peripheral blood progenitor cell transplantations

BACKGROUND

Although controlled-rate freezing and storage in liquid nitrogen are the standard procedure for peripheral blood progenitor cell (PBPC) cryopreservation, uncontrolled-rate freezing and storage at -80 degrees C have been reported.

STUDY DESIGN AND METHODS

The prospective evaluation of 109 autologous PBPC transplantations after uncontrolled-rate freezing and storage at -80 degrees C of apheresis products is reported. The cryoprotectant solution contained final concentrations of 1-percent human serum albumin, 2.5-percent hydroxyethyl starch, and 3.5-percent DMSO.

RESULTS

With in vitro assays, the median recoveries of nucleated cells (NCs), CD34+ cells, CFU-GM, and BFU-E were 60.8 percent (range, 11.2-107.1%), 79.6 percent (6.3-158.1%), 35.6 percent (0.3-149.5%), and 32.6 percent (1.7-151.1%), respectively. The median length of storage was 7 weeks (range, 1-98). The median cell dose, per kg of body weight, given to patients after the preparative regimen was 6.34 x 10(8) NCs (range, 0.02-38.3), 3.77 x 10(6) CD34+ cells (0.23-58.5), and 66.04 x 10(4) CFU-GM (1.38-405.7). The median time to reach 0.5 x 10(9) granulocytes per L, 20 x 10(9) platelets per L, and 50 x 10(9) reticulocytes per L was 11 (range, 0-37), 11 (0-129), and 17 (0-200) days, respectively. Hematopoietic reconstitution did not differ in patients undergoing myeloablative or nonmyeloablative conditioning regimens before transplantation.

CONCLUSION

This simple and less expensive cryopreservation procedure can produce successful engraftment, comparable to that obtained with the standard storage procedure.

Effects of long-term storage at -90 degrees C of bone marrow and PBPC on cell recovery, viability, and clonogenic potential

Autologous BM and PB HPC are usually stored from weeks to months until reinfusion after myeloablative chemotherapy. HPC have been stored for up to 16 months at -90 degrees C, using a mixture of 5% DMSO, 6% hydroxyethyl starch (HES), and 4% HSA as a cryoprotectant. Long-term storage (LTS) has usually entailed rate-controlled freezing using 10% DMSO and preservation in liquid nitrogen. The effects of LTS at -90 degrees C on the in vitro cell recovery, viability, and colony-forming unit-granulocyte macrophage (CFU-GM) clonogenic potential of autologous HPC that were not transplanted was studied. Sixteen BM and sixteen PB HPC had been cryopreserved for a median of 53 months (range 27-71) and 35 months (range 26-78), respectively. Samples of frozen HPC were thawed after 48 h, and the nucleated cell count, viability by trypan blue exclusion, and culture for CFU-GM were obtained. Following LTS, the cells were thawed and examined using the same assays. No difference in the median percentage recovery of nucleated cells was found in either the BM or PB HPC between the samples stored for 48 h and after LTS (5.73 x 10(9) versus 5.61 x 10(9) and 6.20 x 10(9) versus 5.78 x 10(9), respectively). In addition, no difference in median percentage viability was found in either the BM or PB HPC sampled at 48 h and at the end of LTS (75% versus 74% and 75% versus 76%, respectively). Finally, the median number of CFU-GM cultured from BM HPC at 48 h was 2.41 x 10(5) (range 0.33-11.01 x 10(5)) and at the end of LTS was 1.93 x 10(5) (range 0.32-10.55), representing a median recovery of 93% (range 19%-308%). Similarly, the median number of CFU-GM cultured from PB HPC was 1.66 x 10(5) (range 0-50.57) and at the end of LTS was 0.93 x 10(5) (range 0-44.9), representing a median recovery of 80% (range 36%-165%). This difference in percentage recovery was not significant (p = 0.514). There was poor correlation between the number of nucleated cells harvested and the percentage recovery of nucleated cells, cell viability, or CFU-GM for either the BM or PB HPC. Similarly, there was poor correlation between the number of CFU-GM in the harvest and their percentage recovery following LTS for both BM and PB HPC. Finally, there was poor correlation between the storage time of the BM or PB HPC and the percentage recovery of nucleated cells, cell viability, and CFU-GM. These data suggest that LTS of HPC at -90 degrees C is not associated with decreased recovery of nucleated cells or in vitro viability and is associated with only a modest decrease in clonogenic potential. This indicates that storage of HPC at -90 degrees C for periods in excess of 3 years is possible.

The influence of cryopreservation on cytokine production by human T lymphocytes

Human T lymphocytes isolated from peripheral blood were cryopreserved at -196 degreesC for different periods of 3, 14, 21, 35, and 50 days. Viability and cytokine-producing activity of T cells were examined before and after cryopreservation. A high recovery (90 +/- 1%) of viable T cells was obtained at each frozen period, indicating that a 10% loss of cells was due to the freezing process rather than the duration of cryopreservation. There was no difference in cell cycle distribution between PHA-treated fresh and frozen lymphocytes. Resting human T cells produced little or no cytokine. After stimulation of fresh T cells with PHA, an apparent increase in cytokine production was noted in IL-2 (35.5 +/- 8.3 pg/ml), IL-6 (1280.4 +/- 64.7 pg/ml), tumor necrosis factor-alpha (874.3 +/- 71.7 pg/ml), interferon-gamma (58.9 +/- 2.2 pg/ml), and granulocyte macrophage-colony-stimulating factor (59.5 +/- 4.4 colonies/5 x 10(4) bone marrow cells). Compared with PHA-activated fresh T cells, all the above cytokines did not diminish in their levels in conditioned medium from PHA-treated frozen T cells thawed at each storage period, suggesting that cryopreservation could well retain the cytokine-producing activity of human T lymphocytes. In addition, our results also revealed that cryopreservation rendered T lymphocytes more responsive to PHA in IL-2 production than fresh T cells.

Long-term cryopreservation: successful trilineage engraftment after autologous bone marrow transplantation with bone marrow cryopreserved for seven years

Successful autologous bone marrow transplantation (ABMT) and peripheral blood stem cell transplantation depend on safe hematopoietic stem cell (HSC) cryopreservation and storage. Several successful methods for cryopreservation and storage have been established and are commonly used all over the world. However, little is known about the effects of long-term cryopreservation on the capacity to sustain a complete immunohematopoietic engraftment. Several authors have investigated stem cell viability after cryopreservation and storage for more than 5 years and reported preclinical good viabilities in terms of dye-exclusion or colony-forming capability in vitro. Only two studies using BM cryopreserved for more than 5 years for transplantation are reported, but they did not provide proof of trilineage engraftment. In February 1997 at our institution, a patient with relapsed non-Hodgkin's lymphoma underwent ABMT with BM harvested in February 1990. He achieved a granulocyte count > 500 x 10(6)/L on day 21 and a self-supporting platelet count > 20 x 10(9)/L on day 30. After day 29, his hemoglobin level was satisfactory without need of transfusion support. This successful trilineage engraftment with cryopreserved BM that had been stored for 7 years suggests that HSC are able to maintain their capability to reconstitute hematopoiesis for a long time.