Regeneration Pancreas

Although other water soluble polymers have also been used, viable mammalian cells have been encapsulated most frequently in stabilized calcium alginate. Sun pioneered this process to microencapsulate pancreatic islets (2). The thin calcium alginate/polylysine capsule wall was able to protect the transplanted islets from the immune system of the host rats (chemically induced diabetes) for 2-3 weeks initially and with further refinement for as much as two years (3,4). The feasibility of this approach has been shown in various animals (5-8). The long term success in rats has been questioned, however, because of the problem of pancreas regeneration in chemically induced diabetic animals (9). 

Significant developments have occurred in recent years in the fields of biopolymers and biomaterials. New synthetic materials have been synthesized and tested for a variety of biomedical and related applications from linings for artifical hearts to artifical pancreas devices and from intraocular lenses to drug delivery systems. Of particular interest in the future is the development of intelligent polymers or materials with special functional groups that can be used either for specialty medical applications or as templates or scaffolds for tissue regeneration. 

Other recently developed biomaterials will be used for quite different purposes in tissue engineering such as artificial pancreas and liver, artificial skin, nerve regeneration, gene therapy vascular grafts, cornea replacement and others.3... 

Histologically, parenchymal necrosis and regeneration and fibrosis are found in the liver, which in addition often contains enormous amounts of stain-able iron and also resembles a typical cirrhotic liver. The pancreas is often smaller than normal and fibrotic both the exocrine and the endocrine glands are necrotic, and the destroyed parenchyma is replaced by connective tissue fibrils. 

Phosphorylation of histones is another mechanism for the neutralization of basic proteins. The phosphorylation reaction occurs after the completion of the histone synthesis. It is reversible. Phosphorylation of the lysine- and arginine-rich histones precedes an increase in RNA synthesis. This was found in transforming lymphocytes, in the regenerating liver and pancreas, etc. Histones and protamines are phosphorylated at the final stages of spermatogenesis (see review of Allfrey et al, 1964, 1972). Specific kinases which participated in the transport of phosphorus groups from ATP to histones are stimulated by cyclic AMP (Allfrey et al., 1972). 

Natural extracellular matrices (ECMs) have been isolated and extracted from various tissues, such as smaU-intestine submucosa, skin (from cadavers), pancreas and breast (Badylak, 2(X)7). Althongh these purified ECMs certainly have useful apphcations, then-use is limited in scope owing to the need for well-defined microenvironments in tissne regeneration and stem-cell transplantation, in which animal by-products and contaminants mnst be limited. Moreover, it has been demonstrated that, besides the spatial framework, tissue-specific ECM cues, namely the constituents and their stractural organization, are... 

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