No abstract

Isolated hepatocytes, harvested from normal rat livers by portal vein collagenase perfusion, can be attached to collagen-coated dextran microcarriers and transplanted by intraperitoneal injection into rats. Survival and function of the transplanted hepatocytes have been demonstrated in mutant rats lacking bilirubin-uridine diphosphate glucuronosyltransferase activity (Gunn strain) and rats with inherited lack of plasma albumin (Nagase analbuminemia rat strain). This simple technique promises to be useful in the treatment of acute liver failure in humans.

Hepatocytes harvested by collagenase perfusion of rat liver were attached to collagen-coated microcarriers and injected intraperitoneally into congeneic or allogeneic bilirubin-UDP-glucuronosyltransferase (EC 2.4.1.17)-deficient (Gunn) rats or allogeneic analbuminemic (NAR) rats. Five days later, the microcarriers were observed to have formed conglomerates chiefly on the anterior surface of the pancreas. Scanning electron microscopy showed hepatocytes attached to the granular collagen-coated surface of the microcarriers and newly formed connective tissue. Light microscopy revealed that the microcarriers formed a lattice with the collagen tissue; hepatocytes were seen within this lattice or on the surface of the microcarriers. Hepatocyte plasma membranes were nucleoside-diphosphatase (NDPase)-positive. Newly formed blood islands, blood vessels containing erythrocytes and leukocytes and NDPase-positive endothelium were observed in close proximity to the hepatocytes and fibroblasts. Transmission electron microscopic examination showed hepatocytes with microvilli and nucleoid-containing peroxisomes with catalase activity. Hepatocytes were present for up to 2 months in congeneic recipients, the longest period of observation after transplantation. After normal microcarrierattached hepatocytes were transplanted into allogeneic Gunn rats, bilirubin glucuronides were present in bile for 6 days. When congeneic Gunn rat recipients were used, bilirubin glucuronides were present in bile throughout the study (28 days); this was accompanied by reduction of serum bilirubin concentrations to nearly normal levels. After injection of normal hepatocytes into allogeneic NAR rats, plasma albumin concentration progressively increased for 6 days and then declined. In NAR recipients which were immunosuppressed with cyclosporin A, peak plasma albumin levels were reached in 14 days and persisted nearly at that level throughout the study (28 days). We describe a technique in which isolated rat hepatocytes, attached to collagen-coated dextran microcarriers, were injected i.p. in homozygous Gunn rats and genetically analbuminemic (NAR) rats. The injected microcarrierattached hepatocytes form conglomerates in the peritoneal cavity. Light and electron microscopic examination of the conglomerates showed differentiated hepatocytes, newly formed blood vessels, and fibroblasts. Function of the transplanted hepatocytes was shown in Gunn rats by biliary excretion of conjugated bilirubin and reduction of serum bilirubin concentration and in NAR rats by the appearance of albumin in the plasma. MATERIALS AND METHODSMale Wistar rats (200-250 g) were purchased from Charles River Breeding Laboratories. Syngeneic Wistar (RHA) rats and congeneic Gunn rats, which have identical genetic make-up with the Wistar (RHA) rats except for the bilirubin conjugation locus, were developed by C. Hansen of the National Institutes of Health and maintained as congeneic strains at the Albert Einstein College of Medicine (Bronx, NY). Analbuminemic (NAR) rats, mutants...

We previously reported a method of intraperitoneal transplantation of liver cells attached to collagen-coated microcarriers, which resulted in prolonged survival and function of the transplanted cells. In the present study, we evaluated the efficacy of liver cell transplantation in providing metabolic support during acute liver insufficiency induced by 90% partial hepatectomy in rats. Ninety per cent of the liver mass (all lobes except the caudate lobe) was resected, and the rats were provided with 5% dextrose orally ad libitum upon regaining consciousness. This regimen results in severe hypoglycemia and death within 48 hr. When microcarrier-attached liver cells were transplanted into syngeneic and allogeneic recipients 3 days prior to 90% partial hepatectomy, significantly higher blood glucose levels were observed (p less than 0.01), compared to the levels in control rats which received injections of microcarriers, liver cells or medium alone. There was a marked improvement in long-term survival (40% survived longer than 28 days; p less than 0.001) in rats transplanted with microcarriers-attached cells. None of the rats given injections of microcarriers, liver cells or medium alone survived beyond 5 days. When liver cells alone or attached to microcarriers were injected intraperitoneally immediately after 90% partial hepatectomy, all rats became hypoglycemic and died within 48 hr, suggesting that vascularization of the transplant is required for function of the transplanted hepatocytes. The results indicate that intraperitoneal transplantation of microcarrier-attached hepatocytes prior to 90% partial hepatectomy in rats provides acute metabolic support resulting in improved survival.

A technique has been developed by the authors that allows hepatocyte attachment on collagen-coated microcarriers resulting in prolonged hepatocyte viability and function both in vivo and in vitro. Rat hepatocytes were obtained by portal vein collagenase perfusion. Intraperitoneally transplanted microcarrier-attached normal hepatocytes into congeneic Gunn rats were functioning 3-4 weeks later, as shown by the presence and persistence of conjugated bilirubin in recipient bile, sustained decrease in serum bilirubin, uptake of Tc99m-DESIDA, and morphologic criteria. Intraperitoneal transplantation of normal microcarrier-attached hepatocytes into genetically albumin deficient rats (NAR) resulted in marked increase in plasma albumin levels (6 days without and 21 days with Cyclosporin A immunosuppression). Microcarrier-attached hepatocytes transplanted after 2 weeks of storage at -80 C into congeneic Gunn rats were viable and functional as assessed by criteria outlined above. An extracorporeal liver perfusion system was developed using the microcarrier-attached hepatocytes that was capable of synthesizing and conjugating bilirubin and synthesizing liver-specific proteins.

Goodson and Hunt showed that wound healing is impaired in streptozotocin (Sz) diabetic rats; we speculated that this impairment results from defective early inflammatory responses to wounding. Because we had shown that supplemental vitamin A stimulates the early inflammatory response to wounding in nondiabetic rats, we studied the effect of supplemental vitamin A on wound healing in rats with Sz-induced diabetes. Male Sprague-Dawley rats were fed a commercial rat chow containing twice the amount of vitamin A recommended by the NRC for healthy rats. The rats ate and drank (tap water) ad libitum. Two-thirds of the rats were injected (intravenously) with Sz 60 mg/kg body weight. All of these rats became diabetic (hyperglycemia greater than 350 mg/dl, hyperphagic, polydipsic, polyuric, glycosuric greater than 2%). Seven days later, half of the Sz-injected rats were continued on the chow (Group 2) while the other half (Group 3) were switched to the chow supplemented with 150,000 units of vitamin A/kg chow. The next day, all were wounded (7 cm skin incisions and s.c. polyvinyl alcohol sponge implants). Similarly wounded saline injected nondiabetic rats ingesting the unsupplemented chow served as controls (Group 1). The wounds of Group 2 rats healed poorly compared to Group 1 (breaking strength of skin incisions, 308 +/- 19 g vs 584 +/- 23 g, p less than 0.001; hydroxyproline of the sponge reparative tissue, 0.87 mg vs 2.40 mg/100 mg sponge p less than 0.001). Supplemental vitamin A (Group 3) did not affect the hyperglycemia, hyperphagia, polydipsia or glycosuria, but increased the breaking strengths of the incisions of the diabetic rats (468 +/- 40 g, p less than 0.001), and the sponge hydroxyproline (2.38 mg/100 mg sponge, p less than 0.001). In another experiment, in which the wounding and start of supplemental vitamin A were delayed until 28 days after streptozotocin administration (50 mg/kg body weight), similar results were obtained. Streptozotocin diabetes also caused a decrease in the cross-linking of reparative collagen as judged by the ratio of breaking strengths of skin incisions before and after formalin fixation. Supplemental vitamin A did not influence this defect. Sz also caused peripheral lymphocytopenia, adrenal hypertrophy and thymic involution which responded to the supplemental vitamin A. Based upon experimental data and theoretical considerations we conclude Sz diabetes causes two defects in wound healing: a) quantitatively (reduction in reparative collagen accumulation) and b) qualitative reduction in the degree of cross-linking of reparative wound collagen. The action of supplemental vitamin A in correcting the impaired wound healing, adrenal enlargement, thymic involution and lymphocytopenia of Sz-diabetic rats is independent of an effect on their disturbed carbohydrate metabolism.

No abstract

No abstract