Our Science – Vogel Website

Jonathan C. Vogel, M.D.

Dermatology Branch Senior Investigator Building 10, Room 12N260 NCI-Bethesda Bethesda, MD 20892 Phone:   301-496-9002 Fax:   301-496-5370 E-Mail:   jonvogel@mail.nih.gov

Biography

Dr. Vogel received his M.D. from Rush Medical College in Chicago in 1981. His training includes an internal medicine residency at the Barnes Hospital of the Washington University Medical Center, St. Louis, and a fellowship at the NCI. Following a 3-year faculty position at the Holland Laboratories of the American Red Cross, Rockville, MD, Dr. Vogel joined the Dermatology Branch in the NCI where he has focused on skin gene therapy and keratinocyte stem cells.

Research

Keratinocyte Gene Therapy
The research goal of this project is to achieve long-term expression of a desired gene in vivo in a significant percentage of keratinocytes by identifying and introducing genes into keratinocyte stem cells (KSC). Skin gene therapy is an area of great potential. There are several potential applications for skin gene therapy that require either transient or long-term expression of a desired gene. One possible application is the correction of inherited skin disorders due to single gene mutations. Included in this category are a number of forms of epidermolysis bullosa (inherited blistering diseases), several of the ichthyoses (keratinization or scaling disorders), xeroderma pigmentosum caused by defective DNA repair genes, and basal cell carcinomas (the most common form of human cancer). We are focusing on another potential application, the use of genetically modified keratinocytes for the systemic delivery of various cytokines, enzymes, and growth factors, such as human insulin and growth hormone. However, achieving long-term expression of desired genes in a significant percentage of keratinocytes has proved to be very difficult. Since unique cell surface markers for keratinocyte stem cells are not yet known, the isolation, purification, and efficient introduction of genes into these cells will be necessary for long-term expression in high percentages of keratinocytes is not yet possible. In order to achieve long-term expression, we have developed an approach using topical colchicine treatments to select for keratinocytes that express a multi-drug resistance (MDR) selectable marker gene along with a linked gene of interest. A significant advantage of this approach is that it does not depend on keratinocyte stem cell identification and targeting. When the selective treatment (colchicine) is applied topically, only keratinocytes that express the MDR selectable marker gene will survive and populate the epidermis. We have recently demonstrated the feasibility of this approach in an in vivo mouse model. When grafted keratinocytes that express MDR are topically selected with colchicine, long-term expression of MDR is maintained in a significant percentage of keratinocytes implying that keratinocyte stem cells expressing MDR have been transduced and selected. Therefore, topical colchicines selection should achieve durable and high level expression of ANP and other therapeutic genes.

Biology of Keratinocyte and Cancer Stem Cells
Another important laboratory effort is to identify unique cell surface markers of KSC in order to distinguish these stem cells from other keratinocytes. Currently, unique cell surface markers have not been identified for either keratinocyte stem cells or other epithelial tissues. The ability to identify and manipulate keratinocyte stem cells is important for two reasons. First, it will allow us to gene target these cells, which is important for long-term gene expression in a renewing tissue. Second, the epidermis and other epithelial are sources for a majority of human cancer and the ability to selectively target therapies to 'cancer stem cells' of these tissues may be critical to effectively treat epithelial-derived cancer. Keratinocyte stem cells are perhaps best identified by their ability to retain a BrdU label, and we have successfully FACS sorted pure populations of these 'label retaining' cells or LRC. (Unfortunately, the detection of BrdU requires that these cells be fixed and permeablized, making them unsuitable for biological studies requiring living cells.) Good progress has been made in identifying membrane proteins in our ongoing collaboration with the Biomedical Proteomics Program at Frederic and we are now working to quantitatively assess and compare the plasma membrane proteins prepared from LRC keratinocytes to control keratinocyte populations with high throughput mass spectrometry (MS) analysis in order to identify unique cell surface markers. Recently, a population of very primitive hematopoietic stem cells (side population or SP cells) have been identified because of unique fluorescent emission characteristics due to their ability to exclude HO33342 nuclear dye. We have recently described a SP population of keratinocytes and are currently trying to determine if these SP keratinocytes function as stem cells in vivo and possess long-term repopulating ability, using our in vivo stem cell assay. We have been using microarray analysis of gene expression in these and control keratinocytes in order to try to understand their function in the skin. Patterns of gene expression in SP keratinocytes can be also be assessed on a protein level, and these SP cells can also be analyzed by high-throughput mass spectrometry for the presence of unique cell surface markers. The experimental approaches we have developed to identify cell surface markers of keratinocyte stem cells can also be applied to cancer stem cells, and the in vivo models we have developed to assess keratinocyte stem cell behavior will be critical in determining if cancer stem cells are present in skin cancers (squamous cell carcinoma and basal cell carcinoma) and in other epithelial cancers. The identity and characterization of cancer stem cells may be required before effective therapies can be developed to treat epithelial cancer.

This page was last updated on 6/12/2008.