Outcome of xenografted fetal porcine pancreatic tissue is superior in inbred scid (C.B-17/Icr-scid/scid) compared to outbred nude (CD-1-nu/nu) mice

Nude mice are used as recipients of foreign tissue because of their inabili ty to reject these grafts. Our experience has been that there is variable r ejection 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 eit her 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 assa yed for insulin content. Mean insulin levels were not significantly differe nt 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 t he nudes than the scid mice, 121 +/- 12 vs. 44 +/- 2 days, the grafts incre asing 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, respective ly. Histologically the grafts in the scid mice contained mostly epithelial cell clusters, a majority of which were insulin containing. In the nude mic e that achieved normoglycemia, a similar pattern was observed and, as well, there was a localized lymphoid infiltrate. In those nude mice that remaine d diabetic fibrous tissue predominated together with a lymphoid infiltrate. In summary, fetal porcine pancreatic tissue grows and develops more effici ently when xenografted into scid rather than outbred nude mice.