Biomedical subjects

Michael V Lioznov

Publications and source records attributed to Michael V Lioznov.

5 recordsLinked to original sources

PubMed2006

Cell growth and differentiation of different hepatic cells isolated from fetal rat liver in vitro.

Stem cells are interesting candidates as a new source for cell/organ culture or cell transplantation concepts. So far it is believed that the hepatoblast is the common progenitor cell during fetal liver development. In previous studies two distinct fractions of liver cells were found during development: cells co-expressing Thy1 and CK-18 (cytokeratin-18) and cells expressing CK-18 only. In this study we cultured Thy1-positive and Thy1-negative hepatic progenitors isolated from collagenase digested fetal rat livers after depletion of OX43/OX44-positive hematopoietic cells. The cells were cultured on a collagen-I matrix in a medium containing epidermal growth factor, insulin, and fetal calf serum. Thy1-positive cells isolated from ED16, ED18, or ED20 livers showed significantly enhanced cell growth compared with Thy1-negative cells during the culture period. Both cell types showed expression of the liver-specific genes CK-18, albumin and alpha-feto-protein at the beginning of the culture period, as assessed by reverse-transcription polymerase chain reaction and immunocytochemistry. The growth of Thy1-positive cells was significantly higher when compared with Thy1-negative cells and declined with maturation of the liver. The data suggest a stem cell-like growth potential of Thy1-positive fetal hepatic cells. Thus, these cells might be useful for concepts of cell-based therapies. However, further efforts must be undertaken to define the biological, ethical, and legal aspects of using fetal cells.

Albumins↗

PubMed2005

High-potential human mesenchymal stem cells.

Bone marrow-derived stromal mesenchymal stem cells (MSCs) have been characterized in vitro by their growth characteristics, the expression of a panel of surface antigens, and their potential to differentiate into mesenchymal lineages. They can be separated by physical methods as well as by immunological or chemical separation or cultivation. Different protocols are used in different laboratories, making the comparison of various reported MSC populations difficult. Here we describe a population of bone marrow-derived adult stem cells that has been separated on a Percoll gradient with low density. It is characterized by an extraordinary high proliferative potential and a conserved phenotype characteristic of MSCs that retain their plutipotentiality in culture, as evidenced by their ability to differentiate into osteo-, chondro-, and adipogenic lineages. Separation of these cells provide an effective and convenient method for rapid expansion of pluripotential human MSCs for clinical use where large amounts of stem cells are needed.

Adipocytes↗

PubMed2003

Hepatic lineages isolated from developing rat liver show different ways of maturation.

Immunocytochemical analysis revealed that different hepatic cell types exist during liver development: (i). cells co-expressing the stem-cell marker Thy1 and the hepatic lineage marker CK-18 and (ii). cells only expressing CK-18 (hepatoblasts). In this study we separated the different hepatic cells and analyzed gene-expression and phenotype. Fetal rat livers were digested by collagenase solution. OX43- and OX44-positive hematopoietic cells were depleted and Thy1-positive cells were enriched using Magnetic cell sorting. The different cell compartments were analyzed by RT-PCR and immunocytochemistry for Thy1, CK-18, AFP, and albumin. Hepatoblasts expressed albumin at all times and AFP in the early stages. Thy1-enriched cells expressed CK-18 at all times, albumin in the early, and AFP in the late stages. Thy1-positive cells from fetal livers express liver specific genes. The data suggest that Thy1-positive hepatic cells develop towards hepatic stem cells, and hepatoblasts develop towards mature hepatocytes of the adult liver.

Albumins↗

PubMed2003

Characterization of cell types during rat liver development.

Hepatic stem cells have been identified in adult liver. Recently, the origin of hepatic progenitors and hepatocytes from bone marrow was demonstrated. Hematopoietic and hepatic stem cells share the markers CD 34, c-kit, and Thy1. Little is known about liver stem cells during liver development. In this study, we investigated the potential stem cell marker Thy1 and hepatocytic marker CK-18 during liver development to identify putative fetal liver stem cell candidates. Livers were harvested from embryonic and fetal day (ED) 16, ED 18, ED 20, and neonatal ED 22 stage rat fetuses from Sprague-Dawley rats. Fetal livers were digested by collagenase-DNAse solution and purified by percoll centrifugation. Magnetic cell sorting (MACS) depletion of fetal liver cells was performed using OX43 and OX44 antibodies. Cells were characterized by immunocytochemistry for Thy1, CK-18, and proliferating cell antigen Ki-67 and double labeling for Thy1 and CK-18. Thy1 expression was found at all stages of liver development before and after MACS in immunocytochemistry. Thy1 positive cells were enriched after MACS only in early developmental stages. An enrichment of CK-18 positive cells was found after MACS at all developmental stages. Cells coexpressing Thy1 and CK-18 were identified by double labeling of fetal liver cell isolates. In conclusion, hepatic progenitor cells (CK-18 positive) in fetal rat liver express Thy1. Other progenitors express only CK-18. This indicates the coexistence of different hepatic cell compartments. Isolation and further characterization of such cells is needed to demonstrate their biologic properties.

Animals↗

PubMed2003

Liver-specific gene expression in cultured human hematopoietic stem cells.

Hematopoietic and hepatic stem cells share characteristic markers such as CD34, c-kit, and Thy1. Based on the recent observations that hepatocytes may originate from bone marrow, we investigated the potential of CD34(+) bone marrow cells to differentiate into hepatocytic cells in vitro. CD34(+) and CD34(-) human bone marrow cells were separated by magnetic cell sorting. Cells were cultured on a collagen matrix in a defined medium containing hepatocyte growth factor. Cell count and size were measured by flow cytometry, and reverse transcription polymerase chain reaction was carried out for the liver-specific markers CK-19 and albumin. During cell culture, CD34(+) cells showed an increasing cell number and proliferative activity as assessed by Ki-67 staining. Under the specified culture conditions, CD34(+) cells expressed albumin RNA and CK-19 RNA after 28 days, whereas CD34(-) cells did not show liver-specific gene expression. The results indicate that CD34(+) adult human bone marrow stem cells can differentiate into hepatocytic cells in vitro.

Adult↗