Faculty Bibliography

Recent findings suggest that bone marrow-derived cells (BMDC) may contribute to tissue maintenance throughout the body. However, it is not yet known whether marrow-derived epithelial cells are capable of undergoing proliferation. Our laboratory has shown that BMDC engraft as keratinocytes in the skin at low levels (</= 1%) in the absence of injury. Here we show that skin damage affects the degree of engraftment of BMDC as keratinocytes and that the keratinocytes are actively cycling. Female mice reconstituted with sex-mismatched BM were wounded by punch biopsy and incision. At the wound site, engraftment of BMDC as epidermal cells increased within 1 day, and continued to increase to approximately 4% by 3 weeks after injury. Using a Cre-lox system, fusion of BMDC with epithelial cells was ruled out. BMDC-derived epithelial cells at the wound edges expressed Ki67, a marker for actively cycling cells, and this proliferation correlated with an increase in the number of donor-derived cells within the wound. Donor-derived cytokeratin 5-expressing cells were rare, suggesting that BMDC do not engraft as epidermal stem cells, and the level of engraftment peaked and then decreased over time, further suggesting that BMDC may assist in early wound healing by engrafting as transit-amplifying cells, which then differentiate into keratinocytes

BACKGROUND AND AIMS: Dysplastic nodules (DN) may be divided into high-grade and low-grade, and the former has been known as a precancerous or borderline lesion. Recently many morphological characteristics concerning these types of DN have been reported. In the present study we attempted to evaluate the scirrhous change in DN as an indicative feature of high-grade DN, based on the morphological and cell-kinetic analyses using immunohistochemical stains for Ki-67. METHODS: We reviewed 35 livers with DN and selected 15 DN with scirrhous change. We stained DN-bearing sections of each case with hematoxylin and eosin, trichrome, reticulin and Perls' stain. We tried to subclassify and characterize the scirrhous change according to the fibrosis pattern. We also stained with Ki-67 immunohistochemically to assess the proliferative activity of DN with scirrhous change. RESULTS: We found two types of scirrhous change, that is, pericellular and stellate. The pericellular type was related to the Mallory body-forming cholestatic degeneration, whereas the stellate type was associated with extensive portal fibrosis probably induced by ischemic damage. Among DN with scirrhous change, high-grade DN comprised five nodules (33%) and there were 10 (67%) low-grade nodules. There was no significant relationship between the presence or the types of scirrhous change and the grade of DN. The significant differences of Ki-67 labeling indices between types of scirrhous change were not shown in this study. We also could not find the differences between Ki-67 labeling indices of scirrhous DN (high and low grades) and those of surrounding regenerative nodules. CONCLUSIONS: This evidence indicated that the scirrhous change in DN was not a specific feature of high-grade DN. We also found that scirrhous DN have two morphological varieties that may represent biologically different processes, that is, pericellular scirrhous type and stellate scirrhous type

Hepatic stellate-cell lipidosis due to hypervitaminosis A can lead to cirrhosis, which can be averted by restricting vitamin A intake. Other causes, including the use of synthetic retinoids, have been postulated. We studied the frequency and etiology of stellate-cell lipidosis in patients undergoing liver biopsy for reasons other than vitamin A abuse. Fourteen cases (1.1%) were identified retrospectively among 1,235 nontransplant liver biopsy specimens examined from January 1995 through December 1999. Diagnostic criteria included the following: lipid-laden cells in the space of Disse; small, dark, crescent-shaped nuclei with inconspicuous nucleoli; and wispy cytoplasmic strands separating fat droplets. Patient details, reason for biopsy, and medication use were studied. Reasons for biopsy included hepatitis C (10 cases), abnormal liver enzyme levels (2 cases), methotrexate use (1 case), and alcohol abuse (1 case). Hypervitaminosis A was not suspected clinically in the 5 patients who used oral vitamin A or 3 who used topical tretinoin (Retin-A). In 6 patients, no cause of stellate-cell lipidosis was discerned. Stellate-cell lipidosis should be reported to alert clinicians to a potentially preventable form of liver injury

Bone marrow harbors cells that have the capacity to differentiate into cells of nonhematopoietic tissues of neuronal, endothelial, epithelial, and muscular phenotype. Here we demonstrate that bone marrow-derived cells populate pancreatic islets of Langerhans. Bone marrow cells from male mice that express, using a CRE-LoxP system, an enhanced green fluorescent protein (EGFP) if the insulin gene is actively transcribed were transplanted into lethally irradiated recipient female mice. Four to six weeks after transplantation, recipient mice revealed Y chromosome and EGFP double-positive cells in their pancreatic islets. Neither bone marrow cells nor circulating peripheral blood nucleated cells of donor or recipient mice had any detectable EGFP. EGFP-positive cells purified from islets express insulin, glucose transporter 2 (GLUT2), and transcription factors typically found in pancreatic beta cells. Furthermore, in vitro these bone marrow-derived cells exhibit - as do pancreatic beta cells - glucose-dependent and incretin-enhanced insulin secretion. These results indicate that bone marrow harbors cells that have the capacity to differentiate into functionally competent pancreatic endocrine beta cells and that represent a source for cell-based treatment of diabetes mellitus. The results generated with the CRE-LoxP system also suggest that in vivo cell fusion is an unlikely explanation for the 'transdifferentiation' of bone marrow-derived cells into differentiated cell phenotypes