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PubMed2002

Fetal brain progenitor cells transdifferentiate to fates outside the nervous system.

Central nervous system stem cells give rise to neurons and glia when exposed to specific trophic factors. In our studies with rat fetal brain-derived stem cells (RSCs), we showed that they could be induced to express the developmentally regulated transcription factors and cell markers characteristic of cells derived from another germ layer, e.g. pituitary cells. Therefore, rat fetal brain-derived stem cells do not seem to be restricted to a defined developmental fate. They may retain pluripotentiality and can be redirected to develop into other cell types not found in the brain provided the correct set of stimuli is present. This multipotent developmental behavior also suggests that instructive signals are operative.

Animals↗
PubMed1989

Bone formation following intrarenal transplantation of isolated murine chondrocytes: chondrocyte-bone cell transdifferentiation?

Isolated syngeneic epiphyseal chondrocytes transplanted into a muscle formed cartilage in which matrix resorption and endochondral ossification began at the end of the second week after transplantation. After 56 days cartilage was converted into an ossicle. In 7-day-old intrarenal transplants, epiphyseal chondrocytes formed nodules of cartilage. In 10-day-old transplants, islands of bone appeared. Slight resorption of cartilage was first noted in 14-day-old transplants of chondrocytes. After eight weeks, transplants contained mainly bone. Intramuscularly transplanted rib chondrocytes formed cartilage which did not ossify. Nevertheless, bone islands appeared in intrarenal transplants of rib chondrocytes. Bone was not formed in allogeneic intrarenal transplants of epiphyseal or rib chondrocytes, but appeared in such transplants in animals immunosuppressed by anti-thymocyte serum and procarbazine. When spleen cells from animals immunized with allogeneic chondrocytes were transferred to immunosuppressed chondrocyte recipients two weeks after intrarenal chondrocyte transplantation, the majority of osteocytes in bone islands was dead. On the other hand, endochondral bone formed in intramuscular transplants of allogenic epiphyseal chondrocytes in immunosuppressed recipients was not damaged by sensitized spleen cells. This suggested that bone in 10- to 14-day-old intrarenal transplants of chondrocytes arose from injected cells and not by induction. To see whether bone was formed by chondrocytes or by some cells contaminating the chondrocyte suspension, the superficial layer of rib cartilage was removed by collagenase digestion and only more central chondrocytes were used for transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Cultured dermal papilla cells induce follicle formation and hair growth by transdifferentiation of an adult epidermis.

Adult rat pelage follicle dermal papilla cells induced follicle neogenesis and external hair growth when associated with adult footpad skin epidermis. They thus demonstrated a capacity to completely change the structural arrangement and gene expression of adult epidermis--an ability previously undocumented for cultured adult cells. Isolation chambers ensured that de novo follicle formation must have occurred by eliminating the possibility of cellular contributions, and/or inductive influences, from local skin follicles. These findings argue against previous suggestions of vibrissa follicle specificity, and imply that the potential for hair follicle induction may be common to all adult papilla cells.

Animals↗
PubMed1999

Transdifferentiation of NRP-152 rat prostatic basal epithelial cells toward a luminal phenotype: regulation by glucocorticoid, insulin-like growth factor-I and transforming growth factor-beta.

The role of basal epithelial cells in prostatic function, development and carcinogenesis is unknown. The ability of basal prostatic epithelial cells to acquire a luminal phenotype was explored in vitro using the NRP-152 rat dorsal-lateral prostate epithelial cell line as a model system. NRP-152, which was spontaneously immortalized and clonally derived, is an androgen-responsive and nontumorigenic cell line that has a basal cell phenotype under normal growth conditions. However, when placed in mitogen-deficient media, these cells undergo a dramatic morphological change to a luminal phenotype. Under these growth-restrictive conditions, immunocytochemical analysis shows that NRP-152 cells acquire the luminal markers Z0-1 (a tight-junction associated protein), occludin (integral tight-junction protein), and cytokeratin 18, and lose the basal markers cytokeratins 5 and 14. Total protein and mRNA levels of cytokeratins 8, 18, c-CAM 105 (the calcium-independent cell adhesion molecule) and Z0-1, as detected by western and/or northern blot analyses, respectively, are induced, while cytokeratin 5 and 15 are lost, and occludin is unchanged. Concomitant with this differentiation, expression of transforming growth factor-beta2 (TGF-beta2), TGF-beta3, and TGF-beta receptor type II (TbetaRII) is induced, while those of TGF-beta1 and TbetaRI remain essentially unchanged. Mitogens, such as insulin-like growth factor-I and dexamethasone inhibit luminal differentiation, while exogenous TGF-beta induces such differentiation. These data together with TGF-beta neutralization experiments using pan-specific antibody implicate an important role for autocrine TGF-beta in the induction of the luminal differentiation.

Animals↗
PubMed2004

No evidence for significant transdifferentiation of bone marrow into pancreatic beta-cells in vivo.

Several recent studies have suggested that the adult bone marrow harbors cells that can differentiate into tissues from all three germ layers. Other reports have contradicted these findings or attributed them to cell fusion. In this study, we investigated whether bone marrow-derived cells contribute to the renewal of adult pancreatic endocrine cells, in particular insulin-producing beta-cells, in vivo. To address this issue, we studied mice transplanted with green fluorescent protein (GFP)-positive, sex-mismatched bone marrow. We also extended our studies to pancreatic injury models (partial pancreatectomy and streptozotocin administration). All animals showed stable full donor chimerism in the peripheral blood and microscopic analysis at 4-6 weeks and 3 months after transplantation, indicating that the GFP(+) and Y chromosome-positive donor bone marrow contributed substantially to blood, lymphatic, and interstitial cells in the pancreas. However, after examining >100,000 beta-cells, we found only 2 beta-cells positive for GFP, both of which were in control animals without pancreatic injury. Thus our study results did not support the concept that bone marrow contributes significantly to adult pancreatic beta-cell renewal.

Animals↗
PubMedDate not supplied

Neoplastic AIDS-associated Kaposi's sarcoma cell line KSY-1 cannot transdifferentiate into capillaries.

OBJECTIVE: Kaposi's sarcoma (KS) is an acquired immunodeficiency syndrome (AIDS)-defining neoplasm histologically characterized by proliferation of spindle cells, inflammatory cells, and abundant neovascularization. When the malignant cell line KSY-1 derived from an AIDS-KS tumor is transplanted subcutaneously into nude mice, prominent neovascular features develop. Using this mouse model of neoplastic KS, we set out to determine, using c-ets 1 markers specific for mouse or human tissues, whether vascular growth and inflammatory infiltrate induced by the transplanted KSY-1 cells is of host cell or transplant origin. STUDY DESIGN/METHODS: KS tumors were induced by subcutaneous inoculation of 5 x 10(6) KSY-1 cells/200 microL in immunodeficient mice, and species-specific mouse and human riboprobes of the c-ets 1 protooncogene were used for in situ hybridization to define cell of origin. RESULTS: Five different tumors were examined. Tissue sections from all cases were hybridized with radiolabeled riboprobes for the presence of both mouse and human c-ets 1 mRNA. Tumor cells were labeled with the human c-ets 1 probe, whereas neovascular and inflammatory tissues were of mouse origin. CONCLUSIONS: The finding that vascular but not tumor cells are of host origin supports the model of tumor-induced vascularization via a mechanism of tumor cell-derived cytokine-medicated pathogenesis.

Acquired Immunodeficiency Syndrome↗
PubMed2004

[A pilot study on transdifferentiation of skin stem cell in reconstructing corneal epithelium].

OBJECTIVE: To observe the differentiation and development of skin stem cells on corneal stroma and to discuss the possibility of reconstructing corneal epithelium with skin stem cells. METHODS: Pieces of human and rabbit skin were obtained during operation. Rabbit eye balls were taken, and pieces of corneal stroma without epithelium were prepared. Skin stem cells from the rabbit skin and human skin were cultured. The human skin stem cells of the first generation to 4th generation were implanted on the rabbit corneal stroma and cultured. Three rabbits underwent autotransplantation of the rabbit skin stem cells of the first generation to 4th generation on the pieces of corneal stroma with the superficial lamina removed and then fed for 100 approximately 114 days. Another 3 rabbits underwent allotransplantation of the rabbit skin stem cells of first to 4th generation on the pieces of corneal stroma with the superficial lamina removed and then fed for 100 days. Then the rabbits were killed and their eye balls taken out. The rabbit corneas implanted with human or rabbit epithelial cells and the rabbit corneas with the autogeneous or heterogeneous epithelial cells were sliced and underwent immunohistochemistry with human AE5 antibody corresponding to the specific surface marker keratin K3/K12 common to humankind and rabbit, and human epithelial cell keratin K-19 monoclonal antibody. RESULTS: Since the 3(rd) day of transplantation the transplanted human epithelial cells formed multiplayer and were human AE5 antibody and human K19 monoclonal antibody positive. The autotransplanted corneas remained basically transparent without obvious vascular hyperplasia till the cornea specimens were taken. Histological examination showed intact multiplayer epithelium and immunohistochemistry showed human AE5 positive. The allotransplanted\rabbit corneas showed congestion since the 9(th) day. Histological examination showed that the corneas were nor so transparent as the autotransplanted ones and the epithelium was nor intact with a lot of lymphocyte infiltration. CONCLUSION: Corneal epithelium can be reconstructed from skin stem cell, which may be an alternative for constructing autogeneous bioengineered corneas.

Animals↗
PubMed2004

[Signal transduction on transdifferentiation of renal tubular epithelial cell].

It is an important cell biological phenomenon that epithelial cells transit into mesenchymal cells under special physiological and pathological condition. In recent years, it has been known that epithelial-mesenchymal-transition may be mediated by several intracellular signaling pathways, such as MAPK, Rho, Src, PI3 kinase and Smads. Renal tubular epithelial cells have been observed to transit to myo-fibroblasts in renal diseases. However, the intracellular signaling pathways are rarely known. The progress on this field is reviewed.

Animals↗
PubMed2005

[Investigation of mesenchymal-epithelial transdifferentiation in the morphogenesis mechanism of embryonic epidermic cells].

OBJECTIVE: To study the relationship between the morphologic mechanism of human embryonic epidermic cells and mesenchymal-epithelial transformation (MET) and its modulation factor. METHODS: Morphological occurrence of epidermis was detected with histologic methods in earlier period [estimated gestational age (EGA) 6-14 weeks] human embryonic skin samples. At the same time, the characteristic expression and their distribution markers of mesenchymal cells [vimentin and alpha-smooth muscle actin (alpha-SMA)], embryonic specific epidermic protein CK8&18, specific protein of epidermic stem cell CK19, transforming growth factor-beta1) (TGF-beta1) and its receptor (TGFbetaRI) in embryonic epidermis were examined with immunohistochemistry and indirect-immunofluorescent doble-labelling method. RESULTS: During EAG 6-8 weeks, ectodermal cells containing Vim+/alpha-SMA(-) were found to transform into epidermal stem cells with CK8&18+/CK19+. In ectodermal cells, protein expression density of TGFbetaRI was moderate (+ +), while positive signal of TGFbeta1 was weak (+/-). After EGA10 weeks, epidermal cells showed typical morphological characteristics. CONCLUSIONS: At EGA 6-8 weeks, human embryonic skin epidermal cells began to form through MET, in which the signal pathway mediated by TGFbetaRI might play important roles, but the role of TGFbeta1 need to be further studied.

Cell Differentiation↗
PubMedDate not supplied

[Genetic mechanisms of cell transdifferentiation].

Studies have been considered, which concern identification of regulatory genes in adult newts and their expression during retinal and lens regeneration. B.L. Astaurov repeatedly urged to join efforts of geneticists and embryologists in studies of the mechanisms underlying biological phenomena. This was also true for studies of regeneration. Such studies became possible only after introduction of molecular biology methods. Studies of the mechanisms underlying regeneration have been recently carried out jointly by geneticists and developmental biologists. This review presented at the conference dedicated to the 100th anniversary of B.L. Astaurov deals with these aspects in studies of regeneration.

Animals↗