Assessment of Biological Properties of bone marrow mesenchymal Stromal Cell by Ex-vivo Expansion and Differentiation

Abstract

Mesenchymal stromal cells (MSCs) represent a rare population of multipotent stem cells found in many adult tissues. In bone marrow MSCs support haematopoiesis by providing marrow stroma. MSCs have recently emerged as an exciting candidate for cellular therapy due to their hypoimmunogenic properties and ability to differentiate into different tissue types. With the intent of optimizing large-scale expansion of MSCs for clinical use, we compared different culturing conditions for their ability to support growth and proliferation of bone marrow MSCs (BM-MSCs). We evaluated cells cultured in Alpha Modified Eagle Medium (αMEM), Dulbecco’s modified Eagle medium (DMEM) in the presence of either 10% fetal bovine serum (10% FBS), 10% pooled human platelet lysate (10% pHPL) or commercial serum-free formulation (StemPRO® MSC SFM). We concluded that supplementing growth medium with pHPL resulted in superior cell yield than fetal bovine serum (FBS) and comparable to commercial serum-free formulation. Study II was a phase-I human clinical trial, establishing safety of autologous BM-MSC transplantation in nine spinal cord injury patients. For this ex vivo expanded MSCs were injected intrathecally after premedication. All of our patients tolerated the procedure well and no complication was observed during a median follow up of 644 days. Some of the patients with sub-acute disease reported subjective improvement in sensory and neurological functions. Lastly we carried out a phase-I/II trial of MSCs in allogeneic use as a treatment option in treating steroid-resistant graft versus host disease (GVHD). GVHD is a life threatening complication of allogeneic stem cell xii transplantation and only a fraction of patients are cured through steroids. Those who fail to respond to steroid have a very poor prognosis. The patients received third party BM MSCs as their bone marrow MSCs were failing to cope with the immunemediated tissue destruction by donor T cells. A total of 33 MSC infusions were given to 10 patients suffering from acute GVHD (n=3), chronic GVHD (n=5) and overlap syndrome (n=2). Eight out of ten patients are alive after a median follow up of 11 months with five having sustained CR. Three patients with partial response received further doses to sustain response. One of them died of lung infection while others are still alive. One out of the two non-responding patients died after 17 days of MSC therapy due to advanced liver GVHD while the other is having stable disease course. The overall and disease-free survival was 80% and 50% respectively. The patients developed no complication or toxicity related to MSC infusion. Luminex analysis revealed a modest drop after MSC infusion in pro-inflammatory cytokines like IFNγ, TNFα, IL-1β, IL-2, IL-4, IL-6, IL-17A and IL-17F, whereas serum IL-10 levels were slightly raised. Overall a total of 57 preparations of cultured stem cells were made which were transplanted via I.V. or I.T. route with no adverse event or serious complication to report. Therefore it is concluded that MSCs can be safely given in both autologous as well as allogeneic setting as cellular therapy in selected clinical situations. This initial data on safety and efficacy calls for taking these clinical trials into advanced phase with more detailed account of efficacy measures and addition of placebo groups.