# IN VITRO INITIATION OF BIOLOGICAL CALCIFICATION

> **NIH NIH R01** · HOSPITAL FOR SPECIAL SURGERY · 1993 · $166,856

## Abstract

The formation of calcified cartilage during longitudinal bone growth is a
dynamic process which involves cellular action, cell-matrix interactions,
and physicochemical phenomena.  The process leading to biological
calcification has not yet been fully explained.  The long range goal of
this study is to establish which factors govern the initial deposition of
mineral and which regulate the development of that mineral.  This
investigation will use the differentiating chick limb-bud mesenchymal
cell system which, depending on culture conditions, consistently forms
either organized (normal) or randomly (dystrophic) mineralized cartilage
matrices resembling those in tissues.  A combination of physical
chemistry and cell biology techniques will be used to evaluate the roles
of inorganic and organic phosphate, matrix proteins, and vascular
invasion, in cartilage calcification.  Analyses will be based on
quantitative techniques for characterizing the mineral, the organic
matrix, and their interactions.  X-ray diffraction, electron microscopy,
and Fourier transform infrared microscopy will provide data on the nature
of the mineral, its crystal size and perfection, its organization in the
matrix, and its relative abundance.  Immunocytochemistry and
histochemistry, combined with in situ hybridization and analyses of cell
mRNAs provide data on the composition of the mineralizing matrix and the
cells expressing that matrix.  It is postulated that phosphate (P) has a
function in the regulation of calcification beyond its physicochemical
role.  To define this function the following hypotheses will be tested:
a) Removal of P from matrix proteins will prevent chondrocyte-mediated
calcification, b) P exerts its effect on the matrix at the
post-translational rather than the genomic level, c) Mineralization is
dependent on kinase-mediated phosphorylation of matrix proteins, d)
Mineralization is affected by phosphorylation of cellular, as opposed to
matrix, proteins, and e) P ions exert their effects by regulating
mitochondrial and matrix calcium levels, or, by regulating the activities
of enzymes involved in control of initiation of calcification and crystal
growth.  It is further suggested that in vivo mineralization could be
regulated by modification, of those factors which cause initial mineral
deposition.  To determine why mineral forms at discrete sites in the
matrix we will evaluate the hypotheses that the site of initial
mineralization is determined by: a) The presence of specific matrix
proteins, b) The activity, shape, turnover and maturation of the cell,
and c) The presence of degradative activities.  The reason cartilage
calcification starts in the proximity of blood vessels in vivo will be
examined in the culture system by testing hypotheses that a) Vascular
invasion alters pH facilitating initial mineral deposition, b) The
presence of basement membrane proteins promotes mineralization, and c)
Endothelial cells provide factors which accelerate mineralizat...

## Key facts

- **NIH application ID:** 3158282
- **Project number:** 5R01AR037661-07
- **Recipient organization:** HOSPITAL FOR SPECIAL SURGERY
- **Principal Investigator:** ADELE L BOSKEY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1993
- **Award amount:** $166,856
- **Award type:** 5
- **Project period:** 1987-08-01 → 1996-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3158282

## Citation

> US National Institutes of Health, RePORTER application 3158282, IN VITRO INITIATION OF BIOLOGICAL CALCIFICATION (5R01AR037661-07). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3158282. Licensed CC0.

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