Marco Garcia

Actin Cytoskeletal Disruption following Cryopreservation Alters the Biodistribution of Human Mesenchymal Stromal Cells In Vivo

Summary Mesenchymal stromal cells have shown clinical promise; however, variations in treatment responses are an ongoing concern. We previously demonstrated that MSCs are functionally stunned after thawing. Here, we investigated whether this cryopreservation/thawing defect also impacts the postinfusion biodistribution properties of MSCs. Under both static and physiologic flow, compared with live MSCs in active culture, MSCs thawed from cryopreservation bound poorly to fibronectin (40% reduction) and human endothelial cells (80% reduction), respectively. This reduction correlated with a reduced cytoskeletal F-actin content in post-thaw MSCs (60% reduction). In vivo, live human MSCs could be detected in murine lung tissues for up to 24 hr, whereas thawed MSCs were undetectable. Similarly, live MSCs whose actin cytoskeleton was chemically disrupted were undetectable at 24 hr postinfusion. Our data suggest that post-thaw cryopreserved MSCs are distinct from live MSCs. This distinction could significantly affect the utility of MSCs as a cellular therapeutic.

Cryopreserved Mesenchymal Stromal Cells Are Susceptible to T-Cell Mediated Apoptosis Which Is Partly Rescued by IFNγ Licensing.

We have previously demonstrated that cryopreservation and thawing lead to altered Mesenchymal stromal cells (MSC) functionalities. Here, we further analyzed MSCs fitness post freeze‐thaw. We have observed that thawed MSC can suppress T‐cell proliferation when separated from them by transwell membrane and the effect is lost in a MSC:T‐cell coculture system. Unlike actively growing MSCs, thawed MSCs were lysed upon coculture with activated autologous Peripheral Blood Mononuclear Cells (PBMCs) and the lysing effect was further enhanced with allogeneic PBMCs. The use of DMSO‐free cryoprotectants or substitution of Human Serum Albumin (HSA) with human platelet lysate in freezing media and use of autophagy or caspase inhibitors did not prevent thaw defects. We tested the hypothesis that IFNγ prelicensing before cryobanking can enhance MSC fitness post thaw. Post thawing, IFNγ licensed MSCs inhibit T cell proliferation as well as fresh MSCs and this effect can be blocked by 1‐methyl Tryptophan, an Indoleamine 2,3‐dioxygenase (IDO) inhibitor. In addition, IFNγ prelicensed thawed MSCs inhibit the degranulation of cytotoxic T cells while IFNγ unlicensed thawed MSCs failed to do so. However, IFNγ prelicensed thawed MSCs do not deploy lung tropism in vivo following intravenous injection as well as fresh MSCs suggesting that IFNγ prelicensing does not fully rescue thaw‐induced lung homing defect. We identified reversible and irreversible cryoinjury mechanisms that result in susceptibility to host T‐cell cytolysis and affect MSCs cell survival and tissue distribution. The susceptibility of MSC to negative effects of cryopreservation and the potential to mitigate the effects with IFNγ prelicensing may inform strategies to enhance the therapeutic efficacy of MSC in clinical use. Stem Cells 2016;34:2429–2442

The safety of autologous and metabolically fit bone marrow mesenchymal stromal cells in medically refractory Crohn's disease - a phase 1 trial with three doses.

Mesenchymal stromal cells ability to reset immune functionalities may be useful in Crohns disease.

Cryopreserved MSCs are Susceptible to T‐cell Mediated Apoptosis which is partly Rescued by IFNγ Licensing

We have previously demonstrated that cryopreservation and thawing lead to altered Mesenchymal stromal cells (MSC) functionalities. Here, we further analyzed MSCs fitness post freeze‐thaw. We have observed that thawed MSC can suppress T‐cell proliferation when separated from them by transwell membrane and the effect is lost in a MSC:T‐cell coculture system. Unlike actively growing MSCs, thawed MSCs were lysed upon coculture with activated autologous Peripheral Blood Mononuclear Cells (PBMCs) and the lysing effect was further enhanced with allogeneic PBMCs. The use of DMSO‐free cryoprotectants or substitution of Human Serum Albumin (HSA) with human platelet lysate in freezing media and use of autophagy or caspase inhibitors did not prevent thaw defects. We tested the hypothesis that IFNγ prelicensing before cryobanking can enhance MSC fitness post thaw. Post thawing, IFNγ licensed MSCs inhibit T cell proliferation as well as fresh MSCs and this effect can be blocked by 1‐methyl Tryptophan, an Indoleamine 2,3‐dioxygenase (IDO) inhibitor. In addition, IFNγ prelicensed thawed MSCs inhibit the degranulation of cytotoxic T cells while IFNγ unlicensed thawed MSCs failed to do so. However, IFNγ prelicensed thawed MSCs do not deploy lung tropism in vivo following intravenous injection as well as fresh MSCs suggesting that IFNγ prelicensing does not fully rescue thaw‐induced lung homing defect. We identified reversible and irreversible cryoinjury mechanisms that result in susceptibility to host T‐cell cytolysis and affect MSCs cell survival and tissue distribution. The susceptibility of MSC to negative effects of cryopreservation and the potential to mitigate the effects with IFNγ prelicensing may inform strategies to enhance the therapeutic efficacy of MSC in clinical use. Stem Cells 2016;34:2429–2442

Mesenchymal Stromal Cells Derived From Crohn's Patients Deploy Indoleamine 2,3-dioxygenase-mediated Immune Suppression, Independent of Autophagy.

Autologous bone marrow-derived mesenchymal stromal cells (MSCs) for adoptive cell therapy of luminal Crohns disease (CD) are being tested in clinical trials. However, CD is associated with dysregulation of autophagy and its effect on MSCs immunobiology is unknown. Here, we demonstrate no quantitative difference in phenotype, in vitro growth kinetics and molecular signatures to IFNγ between MSCs derived from CD and healthy individuals. CD MSCs were indistinguishable from those derived from healthy controls at inhibiting T-cell proliferation through an indoleamine 2,3-dioxygenase (IDO)-dependent mechanism. Upon IFNγ prelicensing, both MSC populations inhibit T-cell effector functions. Neither a single-nucleotide polymorphism (SNP) rs7820268 in the IDO gene, nor a widely reported CD predisposing SNP ATG16L1rs2241880 modulated the suppressive function of MSCs carrying these haplotypes. IFNγ stimulation or coculture with activated T cells upregulated the expression of autophagy genes and/or vacuoles on MSCs. Pharmacological blockade of autophagy pathway did not reverse the immunosuppressive properties and IFNγ responsiveness of MSCs confirming the absence of a functional link between these two cell biochemical properties. We conclude that autophagy, but not IDO and IFNγ responsiveness, is dispensable for MSCs immunosuppressive properties. MSCs from CD subjects are functionally analogous to those of healthy individuals.

Bone Marrow Mesenchymal Stromal Cells from Patients with Acute and Chronic Graft-versus-Host Disease Deploy Normal Phenotype, Differentiation Plasticity, and Immune-Suppressive Activity

The success of allogeneic hematopoietic stem cell transplantation (allo-HSCT) is often limited by the development of acute and/or chronic graft-versus-host disease (GVHD). The lack of effective therapies to treat steroid-refractory GVHD patients has bolstered clinical evaluation of mesenchymal stromal cell (MSC) therapy for GVHD. Currently, testing of MSCs for the treatment of GVHD has exclusively used allogeneic MSCs despite emerging evidence that MSCs lose their immunoprivileged status in vivo. We hypothesized that autologous MSCs could be a viable alternative MSC source for treating active GVHD. MSCs were isolated and successfully expanded from the bone marrow of 12 volunteers (ages 2 to 55 years) who had allo-HSCT transplants and subsequently developed GVHD. MSCs from subjects with GVHD demonstrated an initial lag in growth compared with healthy control subjects; however, this lag disappeared with continued ex vivo expansion. Immunophenotype and mesodermal differentiation capacity of MSCs from GVHD patients were indistinguishable from that of healthy control MSCs. In vitro immunomodulatory functional analyses also demonstrated that GVHD MSCs were equivalent to healthy control MSCs with regards to dose dependently suppressing T cell proliferation and up-regulating indoleamine 2,3-dioxygenase expression when primed with IFN-γ. Single tandem repeat chimerism analyses further demonstrated that MSCs expanded from GVHD patients were exclusively recipient derived. Based on these data, we conclude that recipient-derived MSCs from patients with GVHD are analogous to MSCs from healthy volunteers and represent a viable option for clinical testing as an immunomodulatory option for symptomatic GVHD.

Human mesenchymal stromal cells suppress T-cell proliferation independent of heme oxygenase-1

Mesenchymal stromal cells deploy immune suppressive properties amenable for use as cell therapy for inflammatory disorders. It is now recognized that mesenchymal stromal cells necessitate priming with an inflammatory milieu, in particular interferon-γ, to exert augmented immunosuppressive effects. It has been recently suggested that the heme-catabolizing enzyme heme oxygenase-1 is an essential component of the mesenchymal stromal cell-driven immune suppressive response. Because mesenchymal stromal cells upregulate indoleamine 2,3-dioxygenase expression on interferon-γ priming and indoleamine 2,3-dioxygenase requires heme as a cofactor for optimal catabolic function, we investigated the potential antagonism of heme oxygenase-1 activity on indoleamine 2, 3-dioxygenase and the impact on mesenchymal stromal cell immune plasticity. We herein sought to evaluate the molecular genetic effect of cytokine priming on human mesenchymal stromal cell heme oxygenase-1 expression and its functional role in differentially primed mesenchymal stromal cells. Contrary to previous reports, messenger RNA and protein analyses demonstrated that mesenchymal stromal cells derived from normal subjects (n = 6) do not express heme oxygenase-1 at steady state or after interferon-γ, tumor necrosis factor-α, and/or transforming growth factor-β priming. Pharmacological inhibition of heme oxygenase-1 with the use of tin protoporphyrin did not significantly abrogate the ability of mesenchymal stromal cells to suppress T-cell proliferation in vitro. Overall, these results unequivocally demonstrate that under steady state and after cytokine priming, human mesenchymal stromal cells immunoregulate T-cell proliferation independent of heme oxygenase-1.

Bone Marrow–Derived Mesenchymal Stromal Cells from Patients with Sickle Cell Disease Display Intact Functionality

Hematopoietic cell transplantation (HCT) is the only cure for sickle cell disease (SCD), but engraftment remains challenging in patients lacking matched donors. Infusion of mesenchymal stromal cells (MSCs) at the time of HCT may promote hematopoiesis and ameliorate graft-versus-host disease. Experimental murine models suggest MSC major histocompatibility complex compatibility with recipient impacts their in vivo function, suggesting autologous MSCs could be superior to third-party MSCs for promoting HCT engraftment. Here we tested whether bone marrow (BM)-derived MSCs from SCD subjects have comparable functionality compared with MSCs from healthy volunteers. SCD MSC doubling time and surface marker phenotype did not differ significantly from non-SCD. Third-party and autologous (SCD) T cell proliferation was suppressed in a dose-dependent manner by all MSCs. SCD MSCs comparably expressed indoleamine-2,3-dioxygenase, which based on transwell and blocking experiments appeared to be the dominant immunomodulatory pathway. The expression of key genes involved in hematopoietic stem cell (HSC)-MSC interactions was minimally altered between SCD and non-SCD MSCs. Expression was, however, altered by IFN-γ stimulation, particularly CXCL14, CXCL26, CX3CL1, CKITL, and JAG1, indicating the potential to augment MSC expression by cytokine stimulation. These data demonstrate the feasibility of expanding BM-derived MSCs from SCD patients that phenotypically and functionally do not differ per International Society of Cell Therapy essential criteria from non-SCD MSCs, supporting initial evaluation (primarily for safety) of autologous MSCs to enhance haploidentical HSC engraftment in SCD.