Detection and characterization of an activity which aligns mesodermal cells into parallel arrays

Area of Science:

• Cell Biology
• Developmental Biology
• Biochemistry

Background:

• Mesenchymal cell migration is crucial for development and tissue repair.
• Understanding factors that regulate cell orientation is key to controlling tissue formation.
• Previous studies have not fully elucidated the molecular mechanisms of directed cell migration.

Purpose of the Study:

• To identify and characterize a factor released by mesodermal cells that influences the orientation of migrating mesenchymal cells.
• To quantify the activity of this Cell Orienting Factor and determine its dose-dependency.
• To investigate the nature of the orienting activity and its potential molecular basis.

Main Methods:

• Utilized FS9 mesodermal cell line conditioned medium to assess effects on mesenchymal cell migration.
• Quantified cell orientation by counting cells around tissue explants and using NIH image analysis.
• Investigated the biochemical properties (heat, trypsin sensitivity) and molecular dependencies (insulin, extracellular matrix proteins, cytokines) of the orienting activity.

Main Results:

• FS9 conditioned medium induced an orderly "halo" of oriented, elongated mesenchymal cells around tissue explants.
• The orienting activity exhibited a dose-dependent relationship, with maximal effect at 50% conditioned medium.
• The activity was heat and trypsin sensitive, suggesting a proteinaceous nature, and required insulin for production in serum-free media.

Conclusions:

• A novel, protein-based Cell Orienting Factor is released by mesodermal cells.
• This factor directs mesenchymal cell migration and alignment perpendicular to tissue explants without altering migration rate.
• The findings suggest a new mechanism for regulating cell patterning during tissue development and repair.