Abstract
Background aimsMesenchymal stromal cells (MSCs) are being extensively researched for cell therapy and tissue engineering. We have engineered MSCs to express the pro-apoptotic protein tumor necrosis factor–related apoptosis inducing ligand (TRAIL) and are currently preparing this genetically modified cell therapy for a phase 1/2a clinical trial in patients with metastatic lung cancer. To do this, we need to prepare a cryopreserved allogeneic MSCTRAIL cell bank for further expansion before patient delivery. The effects of cryopreservation on a genetically modified cell therapy product have not been clearly determined. MethodsWe tested different concentrations of dimethyl sulfoxide (DMSO) added to the human serum albumin ZENALB 4.5 and measured post-thaw cell viability, proliferation ability and differentiation characteristics. In addition, we examined the homing ability, TRAIL expression and cancer cell–killing capacities of cryopreserved genetically modified MSCs compared with fresh, continually cultured cells. ResultsWe demonstrated that the post-thaw viability of MSCs in 5% DMSO (v/v) with 95% ZENALB 4.5 (v/v) is 85.7 ± 0.4%, which is comparable to that in conventional freezing media. We show that cryopreservation does not affect the long-term expression of TRAIL and that cryopreserved TRAIL-expressing MSCs exhibit similar levels of homing and, importantly, retain their potency in triggering cancer cell death. ConclusionsThis study shows that cryopreservation is unlikely to affect the therapeutic properties of MSCTRAIL and supports the generation of a cryopreserved master cell bank.
Highlights
Mesenchymal stromal cells (MSCs) possess a number of unique properties that make them attractive candidates for cellular based therapies
We show that MSCs can be cryopreserved in 5% dimethyl sulfoxide (DMSO) with 95% ZENALB4.5 without a significant adverse effect on cell viability, and those cells can be left for up to 90 min post-thaw without adversely affecting viability.We demonstrate for the first time that cryopreservation does not affect long-term expression of tumor necrosis factor–related apoptosis inducing ligand (TRAIL) and that there is a minimal reduction in migration of thawed cells compared with fresh cells
Cell viability of continuously cultured fresh MSCTRAIL was 87.05 ± 1.20% and this was maintained in standard control cryopreservation media containing 30% fetal bovine serum (FBS), which gave 85.07 ± 1.25% post-thaw cell viability (Figure 1A)
Summary
Mesenchymal stromal cells (MSCs) possess a number of unique properties that make them attractive candidates for cellular based therapies They are readily isolated from multiple adult and neonatal tissues and are easy to expand in ex vivo culture conditions [1]. In addition to being attracted to sites of injury, they show evidence of tumor tropism and incorporation into the tumour microenvironment [3], making them ideal vehicles for the delivery of targeted anti-cancer therapies using both systemic and topical delivery These properties have been harnessed further by genetic modification of MSCs using integrating vectors [4], resulting in long-term stable gene expression without affecting the cells critical characteristics [5,6]. This study shows that cryopreservation is unlikely to affect the therapeutic properties of MSCTRAIL and supports the generation of a cryopreserved master cell bank
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