Number of osteoprogenitor cells in human bone marrow markedly decreases after skeletal maturation

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J Bone Miner Metab 1999;17(3):171-7 Related Articles, Books, LinkOut

Number of osteoprogenitor cells in human bone marrow markedly decreases after

skeletal maturation.

Nishida S, Endo N, Yamagiwa H, Tanizawa T, Takahashi HE.

Department of Orthopaedic Surgery, Niigata University School of Medicine, Japan.

 

Pluripotent mesenchymal stem cells in bone marrow differentiate to osteoblast

progenitor cells.

 

When the bone marrow cells are cultured in vitro, they form colony-forming

units-fibroblastic (CFU-Fs) with exhibiting

osteoblastic features such as expression of alkaline phosphatase (ALP) and

formation of calcified nodules ex vivo.

 

This article describes the effect of growth, maturation, and aging of the

skeleton on human CFU-Fs harvested from human

iliac bone marrow.

 

Human bone marrow cells were harvested from the ilia of 49 women, and were

cultured ex vivo for examination.

 

The 49 subjects ranged in age from 4 to 88 years and were without metabolic bone

disease.

 

These aspirated bone marrow cells from human ilium exhibited osteoblastic

phenotype such as alkaline phosphatase (ALP)

activity, expression of osteocalcin (OSC) and parathyroid hormone-receptor

(PTH-R) mRNA, and the formation of calcified

nodules in vitro.

 

The number of ALP-positive CFU-Fs and the ALP activity were quantified.

 

The highest levels of ALP-positive CFU-Fs were observed in the young group,

particularly in those under 10 years of age.

 

The levels of ALP-positive CFU-Fs declined sharply after 10 years of age; those

above 20 years of age exhibited a lower

number of ALP-positive CFU-Fs, with a gradual decline with increasing age.

 

These results indicate that change in the number of ALP-positive CFU-Fs may be

associated with skeletal growth and

maturation.

 

The results also show that osteoblastic features such as ALP activity and

capability of formation of calcification

nodules were maintained even in the older subjects.

 

These findings suggest that decreased activity of bone formation in the aged

subjects could be, in part, caused by the

decreased number of osteoprogenitor cells differentiating into osteoblasts

because the number of ALP-positive CFU-Fs was

one of the indices exhibiting bone-forming activity in the human marrow stromal

cells.

 

PMID: 10757676 [PubMed - indexed for MEDLINE]

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Here we see that as we age the number of osteoblast forming cells

(osteoprogenitor cells) decline with age which means

less and less osteoblast cells are available to form new bone (less cells in the

" Bank " ) and thus accelerating

osteoblast loss (osteoblast apoptosis) would not probably be a good idea for

those wishing to have strong bones in their

second century.

 

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Good Health & Long Life,

Greg Watson,

http://www.ozemail.com.au/~gowatson

gowatson