Hjj. Verhaar et al., A COMPARISON OF THE ACTION OF PROGESTINS AND ESTROGEN ON THE GROWTH AND DIFFERENTIATION OF NORMAL ADULT HUMAN OSTEOBLAST-LIKE CELLS IN-VITRO, Bone, 15(3), 1994, pp. 307-311
Estrogen/gestagen replacement therapy prevents excess bone loss in pos
tmenopausal women. The mode of action by which these sex steroids exer
t their anabolic effects on bone has not been completely clarified yet
. In this study, 17 beta-estradiol (E(2)), as well as the progestins p
rogesterone (P), dydrogesterone (DD), 20 alpha-dihydroxydydrogesterone
(DHD), medroxyprogesterone acetate (MPA), and cyproterone acetate (CP
A) were able to stimulate the mitogenesis and differentiation of norma
l adult human osteoblast-like (HOB) cells harvested from female trabec
ular bone explants. The different progestins exerted a more pronounced
stimulatory effect on HOB proliferation than E(2) did. The combinatio
n of E(2) with P, DD, or DHD did not result in a statistically signifi
cant further increase of HOB proliferation, as compared with the proge
stins alone. In general, E(2) showed a stronger differentiation-induci
ng effect than the progestins, as measured by histochemical staining o
f the HOB cells for alkaline phosphatase activity. Combining E(2) and
the progestins did not result in a further increase of the number of a
lkaline phosphatase positive cells, compared with E(2) alone. The diff
erent progestins proved to be equally potent in stimulating HOB prolif
eration and differentiation. In conclusion, progestins as well as E(2)
exerted anabolic but differential effects on normal adult human osteo
blasts in vitro.