The size of small polydisperse circular DNA (spcDNA) in angiofibroma-derived cell cultures from patients with tuberous sclerosis (TSC) differs from that in fibroblasts

Cell cultures were derived from angiofibromas of three patients with tuberous sclerosis (TSC), from the unaffected skin of these patients, and from the skin of five healthy donors. The length distributions of the small polydisperse circular DNA (spcDNA) fraction of these cell cultures were then analyzed. Nearly half the spcDNA molecules from the angiofibroma cultures were longer than 0.4 μm, whereas only about 7% exceeded this threshold in the spcDNA preparations from the skin fibroblast cultures. The percentage of the larger size class of spcDNA showed an increase at higher numbers of in vitro passages in all three types of cultures, but this effect was much more conspicuous in the angiofibroma-derived cultures than in those from the skin fibroblasts. An age-dependent increase in the overall amount of spcDNA was only seen in the angiofibroma-derived cultures. Our earlier finding of elevated amounts of spcDNA in angiofibroma cultures was confirmed in cultures from an additional TSC patient.