X. Wu et al., Frequency of stromal lineage colony forming units in bone marrow of peroxisome proliferator-activated receptor-alpha-null mice, BONE, 26(1), 2000, pp. 21-26
The bone marrow stroma, consisting of adipocytes, fibroblasts, and osteobla
sts, develops from a multipotent mesenchymal progenitor. The recently descr
ibed nuclear hormone receptors, known as peroxisome proliferator-activated
receptors (PPARs), regulate transcription of genes involved in adipogenesis
, Consistent with this is the observation that PPAR alpha-null mice exhibit
greater extramedullary adipose stores compared with their wild-type contro
ls. To determine if the status of the PPAR alpha protein also influenced bo
ne marrow stromal cell differentiation, this study compared the frequency o
f colony forming units for bone marrow adipocytes (CFU-A), alkaline phospha
tase-positive fibroblasts (CFU-F/ALP(+)), and osteoblasts (CFU-O) between w
ild-type and PPARa-null mice. The CFU frequencies for all lineages were not
significantly different in either gender at age 3 weeks, independent of th
e PPAR alpha background. However, histologic analysis showed that the cross
-sectional area of the femur in male PPAR alpha null mice was significantly
greater than that of PPAR alpha-null female mice and of both wild-type gen
ders. This was due to an increased marrow cavity space rather than an incre
ased cortical bone area. In addition, while the percentage area of cortical
bone occupied by lacunae was equivalent in the PPAR alpha and wild-type ma
les, this value was significantly greater in PPAR alpha-null female mice co
mpared with wild-type females, At age 3-6 months, no significant difference
was observed in the CFU-A frequencies, based on either PPAR alpha status o
r gender. The wild-type male CFU-F/ALP(+) frequency was significantly great
er than the CFU-F/ALP(+) in all other groups. Although the PPARa status had
no influence on the CFU-O frequency, the number of CFU-O was greater in ma
le than in female mice. Sequential incubation of stromal cells in either ad
ipogenic- or osteoblastic-inducing media did not alter the number of CFU-A
or CFU-O, These results indicate that the PPAR alpha-null genotype does not
influence bone marrow stromal cell numbers. (C) 2000 by Elsevier Science I
nc. All rights reserved.