The isolation of stem cells is a critical technology for the treatment of a wide range of diseases. Since stem cells can proliferate and differentiate, their isolation facilitates transplantation and gene therapies. While progress has been made in the isolation of stem cells through biotin-avidin based immunoadsorption, improvements are needed in order to increase yields, purity and rapidity of processing of stem cells. During Phase I, a new method for the isolation of cells has been developed which is based on proprietary photocleavable reagents. Antibodies conjugated with photocleavable biotins have been produced which bind tightly to streptavidin coated surfaces and are then released by UV-A light. One lead compound developed exhibits significant photocleavage at red-shifted wavelengths. Using this approach, CD34+ myelogenous leukemia KG-1 cells have been successfully captured and photoreleased. In combination with an intracellular free radical scavenger, growth and clonogenic assays reveal no differences compared to non-irradiated cells. Phase II research will be directed at the optimization of this new technology for the capture and photorelease of cells for use in transplantation, rapid cell culturing and identification. Preclinical CD34+ cell isolation and mouse engraftment studies will be conducted at Boston University Medical School using human hematopoietic stem cell-containing specimens. PROPOSED COMMERCIAL APPLICATION: Development of new PhotoInduced Cell Selection, PICS, technology based on photocleavable biotins (PC-Biotin), photocleavable markers (PC- Marker) and PC-antibodies (PC-antibodies) will have commercial applications for the isolation and detection of a wide variety of cells including stem cells, endothelial and pathogens. Potential products include PC-Biotin and PC-Marker compounds, PC-antibody conjugates, photocleavable FACS labels, kits for cell isolation, detection and automated devices for cell separation.