Trial Information

Assessment of the Potential of Hematopoietic Stem Cells to Transdifferentiate Into Salivary Gland and Oral Mucosal Epithelial Cells in Adult Bone Marrow Transplant Patients

Patients with Sjogren's syndrome (1-2 million in the U.S.), and patients exposed to ionizing
radiation during therapy for head and neck cancer (~40,000 new patients/year in the U.S.),
experience severe salivary gland hypofunction. In both patient groups, via different
pathogenic mechanisms, acinar cells in the glands are lost. These cells are the sole site
of fluid production in salivary glands, and such patients cannot produce adequate levels of
saliva, leading to considerable morbidity (xerostomia, dysphagia, dental caries,
oro-pharyngeal infections, and mucositis). In many patients, all parenchymal tissue may be
lost. For this latter group, there is no available therapy as they are not candidates for
either pharmacological or gene therapy if little to no epithelial tissue remains. Recent
reports suggest that organ-specific stem cells can differentiate into cells of other organs.
These findings carry significant implications for possible clinical use. This protocol
will investigate if adult human hematopoietic stem cells (HSC) can transdifferentiate into
salivary gland and oral mucosal epithelial cells. We will recruit female bone marrow
transplant recipients (from existing NHLBI protocols) who have received HSC from a male
donor. This gender-mismatched strategy will allow us to detect cells of donor origin by
using an RNA probe specific to the human Y chromosome. A biopsy of labial minor salivary
glands and a cheek scraping will be obtained from female transplant patients. The biopsy
causes minimal discomfort and the cheek scraping is a non-invasive technique. Both
procedures are used routinely for clinical diagnosis. The samples will be co-stained for
specific genetic and protein markers for salivary gland or oral mucosal epithelial cells,
respectively. Cells positive for these markers (Y chromosome, cytokeratins, mucin 1, and
NKCC1) would indicate that the donor's HSC became functionally competent salivary gland
epithelial cells. This protocol will also examine bone marrow transplant recipients with
chronic Graft-versus-Host Disease (GVHD). These patients show similar complications
(xerostomia and oral mucositis) as those encountered in patients with Sjogren's Syndrome.
We hypothesize that GVHD may provide a positive recruitment signal for HSC to home to
salivary and oral mucosal sites. This protocol will recruit 5 female bone marrow transplant
recipients without GVHD and 5 with GVHD. The primary potential benefit of this study is that
if HSC can turn into salivary gland cells, they could be used to regenerate lost salivary
gland tissues or to seed an artificial salivary gland for patients with irreversible
salivary gland damage.