1. PROJECT: NRSP-8: Swine Genome Committee
  2. COOPERATIVE AGENCY/PRINCIPAL LEADERS
  3. Kansas State University: Deryl Troyer

    Collaborating scientists: Mark Weiss, Kathy Mitchell and Duane Davis, KSU

  4. PROGRESS OF WORK AND PRINCIPAL ACCOMPLISHMENTS

We recently identified cells with stem cell potentials from an unexpected source, Wharton’s jelly of the umbilical cord. We call these cells umbilical cord matrix stem (UC) cells based on their source and our preliminary data indicating their potential to differentiate along a neural pathway in vitro. Other characteristics identifying umcs cells as stem cells are the expression of alkaline phosphatase and telomerase. Moreover, we have found that a large percentage of these cells are cKIT positive and Oct4 positive. The latter is a marker characteristic of embryonic stem cells. We have been comparing these cells to other adult and neonatal stem cells. We first transplanted them into rodents and are currently testing whether they will engraft in porcine tissues.

 

Rat nigrostriatal neurons were lesioned by stereotaxic injection of 6 hydroxydopamine into the right caudate-putamen. PKH26 dye loaded or eGFP expressing UC cells were xenotransplanted into the lesioned area. After 2-5 weeks, the rats were sacrificed and their brains sectioned for analysis. Porcine xenografted UC cells did not elicit an observable immune response as demonstrated by absence of inflammation, CD4 or CD8 cells, and appeared to thrive in their new environment. To determine whether the UC cells differentiated into neurons or glia, or remained relatively undifferentiated, immunocytochemistry was utilized. There were some putative PKH26-containing cells that appeared positive for GFAP, an astrocyte-specific protein, as well as TUJ1, NSE and GABA which are neuron-specific proteins. Moreover, a significant percentage of tyrosine hydroxylase cells were observed. These results suggest that UC cells can incorporate into nervous tissue and that they produce little or no cell surface antigens capable of initiating a host-immune response.

Bone marrow stromal cells (BMSCs) are multipotent cells that can differentiate into bone, cartilage, fat, muscle, tendon and other mesenchymal tissues. Thus they are an attractive candidate for ex-vivo gene therapy or other modifications to enhance the health and well being of animals and humans. Several studies have demonstrated that BMSCs can differentiate and colonize adult tissues in vivo. To test whether it might be possible for bovine BMSCs to populate porcine fetal tissues, we cultured bovine BMSCs and injected them into fetal pig livers at day 42 and 45 of gestation. We found that significant numbers of stem cells of bovine origin had populated developing porcine muscle as well as other tissues such as cartilage.

 

4. USEFULLNESS OF FINDINGS

Identification and description of adult and embryonic stem cells is an exciting field touching virtually all disciplines of biological and medical study. While use of human embryonic stem cells remains extremely controversial other discoveries have revealed unexpected potentials for stem cells from adult tissues. Food animal embryonic stem cells have remained an elusive goal.

We have demonstrated that multipotent stem cells (UC cells) can be harvested from a novel tissue and maintained in vitro for long periods of time. These cells are harvested non-invasively and are derived from an inexhaustible source. It may be possible to genetically modify donor cells ex vivo so that fetal grafts can be used to deliver genes resulting in leaner and/or more efficiently produced muscle. The cells may also be engrafted postnatally to deliver growth factors, immune modulators or other gene products to enhance animal performance and/or growth.

 

5. WORK PLANNED FOR NEXT YEAR

We are planning a series of experiments on postnatal injection of these cells as cellular allografts. We are also doing blastocyst injections and embryo transfer to determine whether these cells are capable of forming balanced chimeras.

 

6. PUBLICATIONS ISSUED OR MANUSCRIPTS APPROVED

 

Martin PL, Davis D, Weiss M, Grieger D, Abou-Easa K, Troyer D: Xenotransplantation of bovine bone marrow stromal cells into fetal pigs: incorporation into skeletal muscle. Animal Biotechnology 12(2):183-191, 2002.

Troyer DL, Weiss ML, Mitchell KE, Martin PL, Davis DL: Incorporation of bovine bone marrow stromal cells into porcine fetal tissues after xenotransplantation. Anatomia Histologia Embryologia In Press.

Mitchell K, Weiss M, Mitchell B, Martin P, Davis D, Morales L, Helwig B, Beerenstrauch M, Abou-Easa K, Hildreth T, Troyer D: Matrix cells from Wharton’s jelly form neurons and glia. Stem Cells 21(1):61-70, 2003.