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Biomedical subjects

C Ricordi

Publications and source records attributed to C Ricordi.

At least 289 records · Page 16Linked to original sources
PubMed1989

Effect of in vitro culture and cyclosporine A treatment on adrenal medulla allograft survival.

Adrenal medullary tissue from Wistar-Furth rats was transplanted beneath the renal capsule of Lewis rats to determine the effect of in vitro culture of the donor graft and temporary recipient immunosuppression with Cyclosporine A (CsA) on allograft survival. The adrenal medulla was transplanted immediately after dissection or after 1 week of culture, either at 24 degrees C or in the presence of 95% O2 at 37 degrees C. The results showed that neither cultural pretreatments affect the survival of the isografts as indicated by morphologic integrity of the grafts 30 days after transplantation. In the absence of in vitro culture of the donor medulla and short-term CsA recipient treatment, all the allografts were completely rejected at 30 days. Cultural pretreatment of the grafts either at 24 degrees C or in the presence of 95% O2, in conjunction with temporary CsA treatment of the recipient, or CsA treatment alone produced histologic survival of the grafts 30 days after transplantation. Varying degrees of lymphocytic infiltration were present in the grafts. When adrenal cortex was transplanted in conjunction with medullary tissue a bimodal immune reaction was observed; medullary tissue was infiltrated by lymphocytes, while the adrenal cortex remained morphologically intact with no infiltration at all. The experiments performed did not show a benefit in prolonging medulla allograft survival using pretransplant culture of the tissue.

Adrenal Cortex↗
PubMed1989

Effect of transplantation site and alpha L3T4 treatment on survival of rat, hamster, and rabbit islet xenografts in mice.

Rat, hamster, and rabbit islets were transplanted into diabetic C57BL/B6 mice. The effect on islet xenograft survival of low-temperature culture of the donor islets, alpha L3T4 treatment of the recipients for seven days, and transplantation of the grafts either in the renal capsule or in the liver via the portal vein was determined. Renal capsule transplants of control rat, hamster, and rabbit islets cultured at 37 degrees C for one day produced normoglycemia in the recipients, with the mean survival time (MST) of the grafts ranging from 14 to 19 days. Low temperature culture alone did not produce a significant increase in the survival time. Treatment of the recipients with alpha L3T4 produced a marked prolongation of xenograft survival for all three species receiving renal subcapsular transplants of control or low temperature cultured islets. The range of MST* was from 34 to 46 days. The intrahepatic site produced an even further prolongation of the survival of concordant rat islet xenografts treated in this manner, with 60% of the recipients still normoglycemic at 100 days after transplantation. This enhancing effect of the intrahepatic site on survival did not occur with the discordant xenografts of hamster and rabbit islets.

Animals↗
PubMed1989

Automated islet isolation from human pancreas.

An automated method for the isolation of human pancreatic islets is described. The procedure meets the following requirements: 1) minimal traumatic action on the islets, 2) continuous digestion in which the islets that are progressively liberated can be saved from further enzymatic action, 3) minimal human intervention in the digestion process, and 4) high yield and purity of the isolated islets. After purification of Ficoll gradients, an average of 2279 islets/g pancreas was obtained, with an average purity of 79% islets. The average volume and average insulin content of the final islet preparation were 348 mm3 and 93.4 U, respectively. The islets were morphologically intact with a normal degree of beta-cell granulation, responded to glucose stimulation with a fivefold increase of insulin secretion over basal levels, and produced normoglycemia after transplantation into diabetic mice. The procedure is being used in the second phase of clinical trials of islet transplantation in patients with insulin-dependent diabetes mellitus.

Autoanalysis↗
PubMed1989

Trophic factors from pancreatic islets in combined hepatocyte-islet allografts enhance hepatocellular survival.

The purpose of this study was to determine the effect of pancreatic islets on the survival of clusters of rat hepatocytes transplanted across a major histocompatibility barrier into an ectopic site. Aggregates of hepatocytes and pancreatic islets were obtained from Wistar-Furth rats by an automated method of collagenase digestion. Approximately 8000 Wistar-Furth hepatocyte clusters (100 to 300 micron diameter) were transplanted beneath the renal capsule of Lewis rats with or without the addition of 800 pancreatic islets. Recipients received subcutaneous injections of cyclosporine A (CsA): 30 mg/kg on days 0, 1, and 2, 10 mg/kg on days 3 to 7, and 10 mg/kg every other day for days 8 to 28. In the absence of CsA recipient treatment, all the allografts were rejected within 7 days. The combined hepatocyte-islet allografts in recipients treated with CsA showed maintenance of morphologic integrity of both hepatocytes and islet cells 1, 2, and 4 weeks after transplantation, whereas in the absence of pancreatic islets, the hepatocellular aggregates degenerated despite CsA treatment, leaving only a thin rim of hepatocytes immediately adjacent to the renal parenchyma. It can be concluded that in immunosuppressed recipients hepatocyte-islet renal subcapsular allografts survived despite the presence of an intact liver, which indicates a possible role of trophic factors released locally from the islets.

Animals↗
PubMed1989

Hepatic insufficiency after portacaval shunting is prevented by prior intraportal pancreatic islet autotransplantation.

The extrahepatic diversion of essential splanchnic hepatotrophic factors may cause the liver atrophy and insufficiency that follows portacaval shunting. To investigate this, control dogs with end-to-side portacaval shunts (control-PCS, n = 6) were compared with dogs shunted 1 month after intraportal pancreatic islet autotransplantation (islet-Tx-PCS, n = 5). From the distal pancreas of each experimental dog, 1.95 +/- 0.49 X 10(5) islets were isolated by collagenase digestion and retransplanted within 3 hours. Assays of hepatocellular function (caffeine clearance) and hepatic blood flow (indocyanine green), conventional biochemical liver function tests, and glucose, insulin, and glucagon responses to intravenous glucose challenge were measured monthly and when dogs were killed. Four of six control-PCS dogs were killed 32 +/- 9 days after shunting because of more than 20% body weight loss; one control-PCS dog lost only 7% of body weight by day 56 and stabilized. No significant loss of body weight occurred in islet-Tx-PCS dogs (n = 5). Liver function test abnormalities seen in control-PCS dogs were absent in islet-Tx-PCS dogs. Both control-PCS and islet-Tx-PCS indocyanine green half-life measurements were significantly (p less than 0.05) prolonged at all times, indicating equally reduced hepatic blood flow after shunting for both groups. In contrast, islet-Tx-PCS caffeine half-life periods were significantly (p less than 0.05) shorter than in control-PCS dogs and were similar to those in normal dogs, indicating a protective effect of the transplanted islets on hepatocellular function. We conclude that intraportal pancreatic islet autotransplants prevent, by the local release of hepatotrophic factors within the liver, the metabolic abnormalities and loss of hepatic function after PCS.

Animals↗
PubMed1988

Delayed extra-adrenal epinephrine secretion after bilateral adrenalectomy in rats.

Regulated systemic extra-adrenal epinephrine secretion has been demonstrated in long-term bilaterally adrenalectomized humans. To determine whether this is demonstrable immediately after adrenalectomy and therefore presumably ongoing when the adrenal medullas are intact or if it develops over time after the adrenal medullas are removed, we measured plasma catecholamine concentrations before and serially after bilateral adrenalectomy with cortical reimplantation in rats. We found plasma epinephrine concentrations to decrease from 244 +/- 41 pg/ml to levels that were not convincingly detectable, using a single-isotope derivative assay with a detection limit of 10 pg/ml, for up to 1 wk after bilateral adrenalectomy with cortical reimplantation. Plasma epinephrine concentrations increased thereafter, becoming detectable in all animals and averaging 31 +/- 6 pg/ml 4 wk after adrenalectomy. Thus extra-adrenal epinephrine secretion appears to be a delayed response to removal of the adrenal medullas and cannot be assumed to be ongoing when the adrenal medullas are intact.

Adrenal Cortex↗
PubMed1988

Automated method for isolation of human pancreatic islets.

We describe an automated method for the isolation of human pancreatic islets. The procedure meets the following requirements: 1) minimal traumatic action on the islets, 2) continuous digestion in which the islets that are progressively liberated can be saved from further enzymatic action, 3) minimal human intervention in the digestion process, and 4) high yield and purity of the isolated islets. After purification on Ficoll gradients, an average of 164,600 islets/pancreas was obtained (2279 islets/g), with an average purity of 78.5% islets. The average volume and average insulin content of the final islet preparation were 348 mm3 and 93.4 U, respectively. The islets were morphologically intact with a normal degree of beta-granulation and responded to glucose stimulation with a fivefold increase of insulin secretion over basal levels. The procedure is now being used for the initiation of the second phase of clinical trials on human islet transplants.

Cell Separation↗
PubMed1987

Low-temperature culture of human islets or in vivo treatment with L3T4 antibody produces a marked prolongation of islet human-to-mouse xenograft survival.

In previous studies we have shown that rejection of islet xenografts transplanted between closely related species (rat to mouse) can be prevented by destruction or alteration of antigen-presenting cells in the donor islets and temporary immunosuppression of the recipients. Relatively few studies have been reported on the survival of islet xenografts transplanted between widely discordant species. In the present study, isolated human islets were transplanted beneath the renal capsule of B6 mice made diabetic by the injection of streptozotocin. The effect of culturing the human islets at 24 degrees C for 7 days with or without the administration of anti-L3T4 for 7 days after transplantation was determined. A marked prolongation of the mean survival time was obtained with low-temperature culture alone (greater than 40.2 +/- 9.9 days), with anti-L3T4 alone (greater than 45.2 +/- 6.3 days), and with the combination of these regimens (greater than 51.9 +/- 5.1 days) as compared to controls (7.5 +/- 1.1 days). The surprising finding was the marked effect of low-temperature culture alone on prolonging human islet xenograft survival because this treatment of the donor islets had no effect on the survival of rat islet xenografts. Intact human islets were present in approximately equal to 80% of the recipients after returning to a diabetic state, whereas xenografts of rat islets were completely destroyed. The findings indicate that complete rejection of islets across this widely discordant species barrier is slower than across a closely related barrier and may be occurring by a different rejection process.

Animals↗
PubMed1987

Effect of low-temperature culture and site of transplantation on hamster islet xenograft survival (hamster to mouse).

Isolated hamster islets were transplanted either into the liver via the portal vein or into the renal subcapsular space of diabetic C57BL/6J mice. The mean survival time (MST) of hamster islets cultured overnight at 37 degrees C was 8.5 +/- 0.6 days when transplanted into the liver as compared to an MST of greater than 21.7 +/- 4.9 days with 1 recipient still normoglycemic at 60 days when the islets were placed in the renal subcapsular space. Low-temperature culture (24 degrees C) of the hamster islets for 7 days produced a further significant prolongation of xenograft survival when the islets were placed beneath the renal capsule (MST greater than 43.3 +/- 4.7 days) with 2 recipients normoglycemic at 60 days. A single injection of anti-T-lymphocyte serum in conjunction with low-temperature culture did not produce a further increase in MST; however, 3 recipients were normoglycemic at 60 days. Removal of the kidney bearing successful xenografts at 60 days resulted in a rapid return to the diabetic state. It was interesting that the xenografts maintained normoglycemia in the mice at a level equivalent to the normal hamster (66.2 +/- 4.7 mg/dl) instead of the nonfasting level found in normal C57BL/6J mice (128.4 +/- 6.4 mg/dl). The findings indicate that low-temperature culture of the donor islets in conjunction with using the renal capsule as the site of transplantation produced a marked prolongation of hamster islet xenograft survival. Slow rejection of the xenografts did occur in this site, and histologic studies indicated that this rejection may be antibody mediated.

Animals↗
PubMed1987

Use of culture and temporary immunosuppression to prolong adrenal cortical allograft survival.

Life-long corticosteroid replacement therapy is today the only form of treatment for adrenal insufficiency. The transplantation of adrenal cortical tissue could represent a more physiological approach to the treatment of this syndrome. Successful experimental transplantation of other endocrine tissues across major histocompatibility barriers encouraged us to attempt similar approaches with the adrenal cortex. Recipient rats received bilateral adrenalectomy, followed by the implantation of adrenal cortical tissue beneath the renal capsule. The tissue was transplanted either immediately after its isolation or after pretreatment with 1 week of culture (either at 24 C or in the presence of 95% oxygen). The results show that 1 week of culture of the donor tissue followed by short term treatment of the recipients with cyclosporine A allows long term (30 days) survival of the transplanted adrenal cortical tissue in all animals.

Adrenal Cortex↗