%0 PDF %T Engineering environments to prolong in vitro survival of human hematopoietic stem cells. %A Glettig, Dean. %8 2017-04-18 %R http://localhost/files/x633fc98z %X Abstract: Slight abnormalities in the bone marrow can have very severe consequences, which can be observed in many bone marrow-related diseases, the most well known one being leukemia. To date very limited treatment options exist for theses diseases and generally a stem cell transplant is required for a full cure. These transplants are not only risky but often fail at the stage of search for a compatible donor. A major reason for the absence of potent treatment alternatives is that many molecular and cellular interactions within the bone marrow are still unknown. To advance the cure of bone marrow-related diseases, several groups are trying to develop a sustainable and functional human bone marrow model that can serve two long-term purposes: * Assess the effects of new drugs on bone marrow cells prior to human trials. This will not only remove xenogeneic risks, but likely also reduce the need for animal testing. * Provide long-term proliferation of whole bone marrow in vitro as a practical and cost effective source of stem cells. These cells can be used for research but also help to establish a bank with a wide range of stem cells that will facilitate donor matching for transplants. We have worked towards achieving these long-term goals by designing environments that extend hematopoietic stem cell (HSC) culture time in vitro. Specifically we increased HSC survival rate by: * Determining an optimal medium for stem cell engraftment that supports both proliferation and quiescence. * Adding adipocytes to currently established feeder layer models to inhibit stem cell differentiation. * Creating a 3D construct and perfusion system that supports long-term culture. Using our methods we concluded the following: * There are two CD34+ populations within the bone marrow that differ in size. * The smaller cells are more quiescent and possibly more primitive than the larger cells. * hMSCs differentiation potential rapidly declines when expanding using traditional culture methods. * The use of the conventional markers for hMSCs does not suffice in the definition of a true stem cell. * The use of the more novel markers CD146 and CD271 would more likely be appropriate markers of stemness. * hASCs had an increased CD34 expression when compared to hMSCs. * An improvement of CD34+ in vitro survival rate was achieved when using a feeder layer containing adipocytes. * Direct cell-cell contact is necessary for the expansion of the hHSCs. * Long-term culture 2D is limited by the functionality or peeling of the feeder layers. Therefore a construct for 3D bone marrow culture is of great necessity. * Using a multiple seeding method one can obtain a confluent 3D structure on a silk scaffold. * A unidirectional slow perfusion bioreactor is a promising device to maintain in vitro 3D bone marrow culture.; Thesis (Ph.D.)--Tufts University, 2012.; Submitted to the Dept. of Biomedical Engineering.; Advisor: David Kaplan.; Committee: Catherine Kuo, Pamela Yelick, and Clifford Rosen.; Keyword: Biomedical engineering. %[ 2022-10-11 %9 Text %~ Tufts Digital Library %W Institution