Fig. 4.

Localized osteotomy of synostosed cranial suture and replacement with engineered construct. (a) Osteotomy of the synostosed rat posterior interfrontal (PIF) suture. The coronal suture (yellow arrow), and the anterior interfrontal suture (white arrow) are not ossified, per our previous work (23) and were kept intact during surgery. Dura mater was kept intact as in craniosynostosis surgery, thus eliminating the dura as a variable for both control and experimental groups. (b) Implantation of autologous MSCs and microencapsulated TGFβ3 in a collagen carrier in the resected PIF suture. (c) H&E staining showing secondary synostosis 4 weeks after the implantation of a control collagen carrier consisting of autologous MSCs and placebo PLGA microspheres, simulating post-surgical re-synostosis following craniosynostosis surgery. (d) H&E staining showing the formation of a cranial suture analog from autologous MSCs and TGFβ3 delivery, as characterized by a soft tissue interface (STI) between mineralized bone (b) (arrows pointing to the border of new bone formation fronts). Marked expression (dark brown stain) of bone sialoprotein II (BSP II) and osteopontin (OPN) in re-synostosed cranial suture implanted with a placebo treated implant (e and g). In contrast, BSP II and OPN, two late osteogenesis markers, were not immunolocalized to the engineered soft tissue interface (STI), but showed expression in the newly formed bone (b) in the osteotomized PIF suture treated with autologous MSCs and control-released TGFβ3 (f and h).