Isolation and differentiation of bovine mammary gland progenitor cell populations.
OBJECTIVE
To isolate bovine mammary gland cells with stem cell characteristics.


METHODS
Monolayers of bovine mammary gland cells.


METHODS
Mammary gland cell populations were separated by use of selected media supplements. Phenotypic characteristics were examined via light and transmission electron microscopy. Cellular expression of casein and connexin 43 was identified immunohistochemically. A scrape-loading and dye transfer assay was used to examine the mammary gland cell populations for homogenous gap junctional intercellular communication (GJIC).


RESULTS
Subpopulations of mammary gland cells grown in vitro are classified on the basis of their distinct morphologic features and ability to communicate via gap junctions. Ultrastructurally, 2 morphologically distinct cell types were classified as type I and II cells. Type I cells were small light undiffertiated cells and large light undifferentiated cells that were deficient in functional gap junctions (as is characteristic of stem cells). Type II cells included large light differentiated cells and terminally differentiated cells; GJIC was functional in type II cells. Type II cells had cytoplasmic expression of connexin 43, whereas, type I cells did not. All cells expressed casein.


CONCLUSIONS
Subpopulations of bovine mammary gland cells with stem cell characteristics were identified. Phenotypic differences are observed among type I bovine mammary gland cells with stem cell characteristics. Gap junctional intercellular communication may be necessary for the differentiation of stem cells. Characterization of bovine mammary gland stem cells and their progeny may provide a new tool with which to study mammary gland health.
Holland
Margo S
MS
Department of Veterinary Pathology, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.
Tai
Mei-Hui
MH
Trosko
James E
JE
Griffin
Lorri D
LD
Stasko
Judith A
JA
Cheville
Norman C
NC
Holland
Robert E
RE
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002364:Caseins / Q000032:analysis; D002417:Cattle; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D002469:Cell Separation; D048429:Cell Size; D002478:Cells, Cultured; D018031:Connexin 43 / Q000032:analysis; D005260:Female; D017629:Gap Junctions / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000166:cytology* / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure
D015415:Biomarkers; D002364:Caseins; D018031:Connexin 43