Abstract
Nude mice are used as recipients of foreign tissue because of their inability to reject these grafts. Our experience has been that there is variable rejection of fetal porcine insulin-producing tissue transplanted into CD-1 (athymic) outbred nude mice. To examine the suitability of this line of nude mouse as a recipient of the tissue, fetal porcine pancreas was grafted either into these outbred animals or into an inbred mutant strain of mice, the more immunocompromised severe combined immunodeficient (scid) mouse. Eight weeks after transplantation grafts were recovered from recipients and assayed for insulin content. Mean insulin levels were not significantly different between the two groups of mice, but a wider range of values was obtained from grafts recovered from nude (CD-1-nu/nu) mice. Reversal of diabetes in hyperglycemic recipients was achieved in 4 of 8 nude mice and 8 of 8 scid (C.B-17/Icr-scid/scid) mice. The time taken to achieve this was longer in the nudes than the scid mice, 121 ± 12 vs. 44 ± 2 days, the grafts increasing in size at a slower rate in the nude mice. Time taken for the weight of the grafts to double in size was 94 ± 17 vs. 32 ± 1 days, respectively. Histologically the grafts in the scid mice contained mostly epithelial cell clusters, a majority of which were insulin containing. In the nude mice that achieved normoglycemia, a similar pattern was observed and, as well, there was a localized lymphoid infiltrate. In those nude mice that remained diabetic fibrous tissue predominated together with a lymphoid infiltrate. In summary, fetal porcine pancreatic tissue grows and develops more efficiently when xenografted into scid rather than outbred nude mice.