Figure 6: Engrafted SMA9⁺ progenitors maintain the ability to differentiate into osteoblasts in vivo following secondary transplantation.

A) Experimental design for secondary transplantation.

B) Representative section of a bone that received secondary transplantation. Demeclocycline mineral label was given to the secondary recipient mouse 2 days before euthanasia to provide further confirmation that any engrafted Col2.3GFP⁺ cells were osteoblasts. The presence of Col2.3GFP⁺ cells on the bone surface highlights the long-term osteoprogenitor potential of the engrafted cells. The yellow arrows highlight dual positive (SMA9⁺/Col2.3GFP⁺) osteoblasts on the endosteal surface, and the red arrow highlights an engrafted osteocyte within the cortical bone matrix. Low-scale bar on merged imaged is 500μm, high-mag scale bars are 100μm. n=3, males: specifically, n=3 separate cultures were made, each from two mice transplanted 3 months prior, and each of these 3 cultures was injected into separate secondary transplantation host mice.