Xenograft sourcing

The use of primary tissue preparations and plasmid probes may lead to nonspecific hybridization (Howell and Kaplan, 1987). Xenogeneic tissues are frequently cultivated in immunodeficient animals and may contain bacterial DNA (episomes, plasmids) and lead to erroneous conclusions. In addition to athymic mouse xenografts, bacterial contamination may occur in tissues from other sources such as patients immunocompromised by disease or chemotherapy (opportunistic infections) or even tissues from healthy individuals from organs rich in bacterial flora (e.g., the gut). Spurious hybridization is easily identified with vector probes and can be avoided using probes generated... 

Antiestrogenic activity of heal all was observed in ovariectomized mice administered an aqueous extract of heal all as the sole source of drinking water (estimated daily intake not specified). The mice were implanted with human endometrial xenografts that remain only when treated with estrogen. Mice treated with estrogen and heal all for 1 month had fewer and smaller xenograft implants compared with their estrogen-treated counterparts that drank only water (Collins et al. 2009). 

Encapsulation. Encapsulation is a technique that allows the cells or tissues from the donor animal to be separated from the human immune system. Usually it does not literally involve a capsule but rather drop>-lets of a viscous gel derived from a nonanimal source such as seaweed. The gel allows the grafted cells to accept nutrients from the human recipient and to diffuse hormones, such as insulin, into the body. At the same time, it protects the grafted cells from attacking antibodies. Encapsulation is not a viable technique for whole organ xenografts. 

However, the effect depends on the source of the fibroblasts. Gingival fibroblasts are useful as autologous transplant cells for tracheal epithehal regeneration (comparable to the epithehum induced by tracheal fibroblasts), whereas nasal and dermal fibroblasts could not serve this function [73]. Other studies have used human xenograft cells in animal models, in particular in the nude mice, to show that human airway cells implanted in such conditioned can regenerate a well-differentiated and functional human epithelium [48,74,75]. 

---