Fms-related tyrosine kinase 3 expression discriminates hematopoietic stem cells subpopulations with differing engraftment-potential: identifying the most potent combination

After the bomb drops: a new look at radiation-induced multiple organ dysfunction syndrome (MODS)

PURPOSE

There is increasing concern that, since the Cold War era, there has been little progress regarding the availability of medical countermeasures in the event of either a radiological or nuclear incident. Fortunately, since much is known about the acute consequences that are likely to be experienced by an exposed population, the probability of survival from the immediate hematological crises after total body irradiation (TBI) has improved in recent years. Therefore focus has begun to shift towards later down-stream effects, seen in such organs as the gastrointestinal tract (GI), skin, and lung. However, the mechanisms underlying therapy-related normal tissue late effects, resulting from localised irradiation, have remained somewhat elusive and even less is known about the development of the delayed syndrome seen in the context of whole body exposures, when it is likely that systemic perturbations may alter tissue microenvironments and homeostasis.

CONCLUSIONS

The sequence of organ failures observed after near-lethal TBI doses are similar in many ways to that of multiple organ dysfunction syndrome (MODS), leading to multiple organ failure (MOF). In this review, we compare the mechanistic pathways that underlie both MODS and delayed normal tissue effects since these may impact on strategies to identify radiation countermeasures.

Bone marrow transplantation temporarily improves pancreatic function in streptozotocin-induced diabetes: potential involvement of very small embryonic-like cells

BACKGROUND

The role of bone marrow (BM)-derived cells in pancreatic beta-cell regeneration remains unresolved. We examined whether BM-derived cells are recruited to the site of moderate pancreatic injury and contribute to beta-cell regeneration.

METHODS

Low-dose streptozotocin (STZ) treatment was used to induce moderate pancreatic damage and hyperglycemia. Enhanced green fluorescent protein-positive (EGFP) BM chimeras were evaluated for beta-cell regeneration after STZ treatment.

RESULTS

To test the hypothesis that pancreatic tissue injury induces a stromal cell-derived factor (SDF)-1 gradient to chemoattract the stem cells, we evaluated the expression of mRNA for SDF-1 in damaged pancreatic tissue. SDF-1 was significantly increased in the pancreas after damage, peaking at day 10. The majority of BM cells expressing mRNA for pancreatic development markers were detected in the subpopulation of CD45/Sca-1/Lin very small embryonic-like (VSEL) cells. VSEL cells mobilized from BM to peripheral blood in response to pancreatic damage, peaking in peripheral blood at day 5, and were enriched in the pancreas 10 to 15 days after STZ treatment. To confirm a role for BM-derived cells in pancreatic beta-cell regeneration, we prepared EGFP-->B6 chimeras. In the EGFP chimeras, EGFP cells were detected around duct and islets and were positive for insulin after STZ treatment. However, STZ-induced hyperglycemia was reduced only transiently (49-77 days) after pancreatic injury.

CONCLUSIONS

These data suggest that VSEL cells are mobilized into injured pancreatic tissue and contribute to beta-cell regeneration. Transplantation of BM-derived cells improves the function of injured pancreas, although the response is not sufficient to restore sustained normoglycemia.