Transplantation von prä-differenzierten adulten Stammzellen
In diesem Projekt werden Knochenmark-Stammzellen isoliert und ebenfalls zum Zellersatz von geschädigtem RPE im Natriumiodate-Modell eingesetzt. Hierbei können die Stammzellen unter die Netzhaut transplantiert oder systemisch injiziert werden. Integration und Differenzierung in RPE-Zellen werden histologisch und morphologisch untersucht.
Age-related macular degeneration (AMD) is the leading cause of severe visual impairment in the elderly in industrialized nations and affects 10-20% of people over age 65. At present time there is no effective treatment to restore lost vision in any of these patients. Damage to the retinal pigment epithelium (RPE) followed by photoreceptor degeneration are critical features of AMD.
One therapeutical approach is to replace the damaged cells with healthy tissue. Unfortunately, transplanted retinal cells (both adult and fetal) do not integrate with host retina and rejection of the transplant is an obstacle to overcome. Furthermore, transplanted RPE cells do not attach to senescent Bruch's membrane efficiently, and do not undergo proliferation and spreading to fill in the defect. Therefore, we would like to study the possible use of stem cells to resolve these problems.
Stem cells derived from the bone marrow (BMSC) of the host apparently have multipotent differentiation possibilities and appear to be able to home to damaged tissue. Although no AMD animal model is available so far, the use of the RPE toxin sodium iodate mimics changes observed in geographic atrophy (dry AMD). It selectively destroys RPE cells after an intravenous injection in a time and concentration depended manner. This gives us the possibility to study the potential of BMSC to replace damaged RPE on Bruch’s membrane in the altered subretinal space.
To accomplish the goal, we will examine the time course of BMSC differentiation along an RPE lineage in culture. This is especially important as lineage commitment and partial differentiation of stem cells in culture prior to transplantation is crucial for efficient incorporation. Therefore, we will harvest the BMSC at different points during their differentiation into RPE in culture, and test their ability to incorporate functionally into damaged RPE in vivo. Furthermore, we will attempt to identify the mechanisms – transdifferentiation or fusion - involved in the process.
If successful, the proposed experiments can further promote the use of BMSC to the point where it could be considered as therapy to repair degenerated RPE.