Project Abstract This is a vastly revised competitive renewal of NIH T32 HL-07910 entitled: ?Basic Science Studies on Gene Therapy of Blood Diseases? which is in its 20th year of funding. The discipline of gene therapy has made clinical advances, but is still an emerging clinical field that has not come close to yet realizing its potential. To continue to advance the field in quality of vector transduction and engrafting vector-transduced hematopoietic stem, progenitor and other carrier cells, we must train the next generation of dedicated pre-doctoral students and post- doctoral/clinical fellows. Our aim is to continue to train this next generation of scientists in the clinically-relevant medical area of gene transfer for effective modulation of normal and abnormal cell growth and for gene therapy to correct blood diseases. We request 4 pre- and 5 post-doctoral slots as allotted in the last competitive renewal. We have an outstanding group of 25 very productive, interactive, well-respected and NIH funded investigators as mentors with their primary and/or secondary faculty appointments in 10 departments of the medical school. These mentors have over their career trained a total of 241 pre-doctoral PhD and 412 post-doctoral students, and have published more than 3,500 papers (2798 original refereed, and 709 reviews/book chapters), many with their trainees. Since the competitive renewal of this program in 2014, we were able to train and/or were in the process of training 10 pre and 10 post-doctoral students, who have published 72 papers [40 (Pre-Doc) and 32 (Post-Doc)]. The Program Director (PD) has trained 21 pre-doctoral and 57 postdoctoral/clinical fellows, has published 795 papers, cited over 63,000 times with an H-Factor of 120, and been continuously funded by the NIH since 1978. He is a recognized authority on hematopoietic stem/progenitor cells, and regulation of hematopoiesis. The Co-PD, is a well-recognized and well-funded productive investigator in the area of gene transfer/therapy, and hematopoiesis during disease who has trained numerous students and fellows. The PD and Co-PD have had their work translated for clinical benefit and have extensive administrative experience. They have worked for many years in the area of gene transfer to enhance gene therapy. The majority of our trainees, since initial funding of this grant in 1999, have gone on to careers in academia and other research intensive areas of employment. Training of our pre- and post-doctoral students entails one-on-one interactions, committee and group mentorship, lab meetings, a special seminar series, and journal club in the area of this training program, didactic courses, ethical training, presentations at scientific meetings and expectations for them to publish in scientific and medical journals, to present their work at national and international meetings and to become productive independent investigators whose work will benefit healthcare in general and gene transfer/gene therapy in specific. Trainees are rigorously picked for their motivation and past productivity. Training efforts are enhanced by strong internal and external advisory board committees.