Portrait of Marc Grynpas

Marc Grynpas



Research Stream: Cell & Tissue Engineering

Email & Telephone: directory.utoronto.ca

Main Appointments

  • Senior Scientist, Samuel Lunenfeld Research Institute, Mount Sinai Hospital
  • Department of Laboratory Medicine & Pathobiology
  • Institute of Biomedical Engineering

Additional Appointments

  • Department of Materials Science & Engineering
  • Division of Orthopaedic Surgery, Department of Surgery

Research Interests

Structure and chemistry of bone mineral and matrix

Bone is heterogeneous, contains local areas which have just mineralized next to local areas which have been mineralized for longer periods of time. This heterogeneity renders analysis of whole bone misleading. We use the density fractionation technique to produce mineralization profiles in which newly-formed bone (low density fractions) can be separated from more mature bone, and we analyze the mineral and matrix m each fraction. In addition to chemical analyses we are using electron microscopy, X-ray and electron diffraction, neutron activation analysis and HPLC techniques. By studying the mineral-matrix interactions of the extracellular matrix of bone we are trying to understand the regulation of bone formation, mineralization and resorption.

Changes in Bone Mineral and Matrix with Age and Diseases

Mineralization profiles are a much more sensitive index of bone tissue age than the age of the animal. In normal physiological conditions there is a shift in the profile towards higher densities with aging. In pathological conditions either localized as in osteoarthritis or generalized as in osteoporosis subtle differences can be detected in the mineralization of the bone, confirming the view that in osteoporosis the nature of the bone changes as well as its quantity. We are correlating changes in bone tissue chemistry and architecture to bone mechanical strength.

Effects of Trace Elements and Drugs on Bone

It is possible to manipulate bones in to change their mineralization profile and therefore change their solubility and other material properties. We have shown that a high fluoride diet shifts bone mineralization profiles in rats as well as reducing bone solubility. We are also studying the affect of stable strontium on bone because strontium increases bone mass. In bisphosphonate treated animals we are studying the long term effects of lack of resorption on bone metabolism in animal models of arthritis and osteoporosis.

More information about this research is available on the Samuel Lunenfeld Research Institute Website.