A renewable source of DNA from patients and family members is needed to evaluate the genetic component of many diseases including IDDM and NIDDM. In the past cells have been transformed in order to immortalize them and provide a continual source of DNA. This procedure is time consuming, expensive and difficult -- thus it makes studies of large populations impractical. In addition, transformation converts normal cells to genetically altered cell lines. This contract is to develop new methods to allow normal cells to be grown in a renewable fashion. This will provide a functionally limitless supply of normal DNA more representative of the starting population of cells. The methods will be easy, reliable, and inexpensive. They utilize the addition of novel small organic molecules to standard culture media. Some of these molecules have already been demonstrated to allow very large numbers of population doublings. Although senescence does eventually occur it takes so long that there is virtually an inexhaustable number of cells. In order to determine the best molecule, Phase I will compare the ability of several unique molecules to increase the population doublings that fibroblasts and lymphocytes undergo in vitro.