Determination of bone volume by osteocyte population

Area of Science:

• Biomedical Engineering
• Cell Biology
• Orthopedics

Background:

• Biological tissues regulate size and mass by controlling cell number during development.
• Organ mass and cell number naturally decrease later in life.
• Osteocyte lacunar density is a measure of bone cell density within the bone matrix.

Purpose of the Study:

• To investigate the relationship between osteocyte lacunar density and extracellular matrix volume in bone.
• To test the hypothesis that bone mass is determined by the control of osteocyte number.
• To explore if bone cell number regulation is a general mechanism for organ size control.

Main Methods:

• Analysis of osteocyte lacunar density in cancellous and cortical bone samples.
• Statistical correlation between cell density and extracellular matrix volume.
• Inclusion of a diverse population sample (males and females, ages 23-91).

Main Results:

• A strong positive correlation (r(2) = 0.98) was found between osteocyte lacunar density and extracellular matrix volume.
• This relationship was consistent across both cancellous and cortical bone types.
• The predictive relationship held true for a broad demographic range.

Conclusions:

• Osteocyte lacunar density is a significant predictor of bone extracellular matrix volume.
• Bone mass appears to be regulated by controlling the number of osteocytes.
• This finding supports the broader concept of social control of cell survival and death in organ size regulation.