The objective of the current proposal is to establish genetic modification of Multipotent Adult Progenitor Cells (MAPCs) with Synthetic Microchromosome vectors (SMCs) as a strategy for application in autologous cell based therapy of Hurler's Syndrome (Mucopolysaccharidosis Type 1). Multipotent Adult Progenitor Cells (MAPCs) are a potentially revolutionary, pluripotent stem cell population isolatable from adult human bone marrow, capable of differentiation along multiple developmental lineages in a controlled, definable manner. BAC (Bacterial Artificial Chromosome) based Synthetic Microchromosomes (SMCs) are a proprietary, non-integrative, gene therapy platform potentially capable of bypassing the technical and operational challenges inherent in conventional retroviral based gene therapy vectors. The specific experimental aims of the program are as follows: 1) Establish the efficiency of de novo microchromosome formation in MAPCs using BAC-based SMC vectors. Molecular techniques will be utilized to establish the presence, structural integrity and stability of the microchromosome. 2) Determine the impact of the microchromosome on the stem cell-like characteristics and differentiation properties of the host MAPC. 3) Demonstrate long term genetic complementation of MAPCs isolated from Hurler's patients using a synthetic microchromosome vector engineered to express a-L-iduronidase under the control of its endogenous regulatory elements. Synergy of the SMC platform with the MAPC technology will likely provide unique solutions to the difficulties inherent in both gene and cell therapy by permitting non-integrative, mitotically stable genetic modification of the patient's own stem cells with non-immunogenic vectors capable of delivering and expressing any gene of therapeutic significance regardless of size or genomic structure. Success in this Phase 1 study as defined by completion of Aims 1-3 above will trigger Phase 2 studies to evaluate the long-term therapeutic potential of genetically modified human MAPCs in vivo in an immunosuppressed Hurler's mouse model.
