Hard tissue therapeutics

A method of determining efficacy of a peptide comprising:

• (a) testing and confirming that the peptide binds integrin αvβ3 expressed on osteocytes, wherein the binding affinity of the peptide to integrin αvβ3 expressed on osteocytes is found to be at least 300 times higher than its binding affinity to the integrins αvβ1, αvβ6, αvβ8, α1β1, α2β1, α3β1, α4β1, α5β1, α6β1, α8β1, α9β1, and α10β1 and wherein the peptide is found to bind integrin αvβ5 with a lower affinity than the peptide's affinity to integrin αvβ3,
• (b) testing and confirming that the peptide is agonistic on binding to integrin αvβ3 expressed on osteocytes, and is not antagonistic, inhibitory, or blocking;
• and
• (c) injecting a subject with the peptide confirmed in step (a) to potentially be efficacious and thereby determining if binding to integrin αvβ3 is at a level so as to result in improving joint function upon injection into a subject;
• (d) testing and confirming that the peptide binding to integrin αvβ3 expressed on osteocytes is at a level so as to result in improving joint function upon injection into a subject.