Dp. Lennon et al., Dilution of human mesenchymal stem cells with dermal fibroblasts and the effects on in vitro and in vivo osteochondrogenesis, DEV DYNAM, 219(1), 2000, pp. 50-62
The stromal elements of human bone marrow include cells, referred to as mes
enchymal stem cells (MSCs), that have the potential to differentiate into b
one, cartilage, fat, and hematopoietic-supportive stromal tissue. MSCs have
been isolated and maintained in culture, and in vivo and in vitro assays h
ave been used to show that these cultured cells possess osteochondral poten
tial. Human mesenchymal stem cells (hMSCs) were combined in a range of prop
ortions with human dermal fibroblasts (hDFs), shown to be devoid of osteoch
ondral potential, and tested in these assays. Results suggest that hMSCs ma
y be intentionally "contaminated" with 25-50% hDFs and still elicit a posit
ive response in alkaline phosphatase and calcium in vitro osteogenic assays
, form cartilage in pellet culture conditions, and produce bone when loaded
into porous hydroxyapatite-tricalcium phosphate ceramic cubes and then imp
lanted subcutaneously into immunocompromised mice. Although hMSCs can be pu
rified and culture-expanded as a homogeneous subset of marrow cells, the di
lution results reported here are encouraging for the prospective use of the
se cells in clinical applications, where repair grafts that contain 100% hM
SCs almost surely will become infiltrated with host connective tissue and v
asculature, which will dilute the initial concentration of hMSCs. (C) 2000
Wiley-Liss, Inc.