Polyethylene glycol formulations show different soft tissue remodelling and angiogenesis features.

Background: Soft tissue regeneration and remodeling is fundamental in periodontal surgery, thus we investigated the angiogenic response elicited in subcutaneous tissue of rats by a proprietary polyethylene glycol hydrogel formulation (PEG) alone, or conjugated with specific amelogenins (EMD) or Nanobioglass particles (NBG). Methods: Discs with three different formulations (PEG, PEG-EMD, PEG-NBG) were inserted into four unconnected subcutaneous pouches, produced on the back of Sprague-Dawley rats (n=56, divdided into 3 groups), and used for blood flow evaluation by Laser Doppler analysis at 1, 2, 4, 8 and 16 weeks or for histological and immunohistochemical analysis at 1, 2, 4, 8 and 16 weeks. Results: All formulations showed tissue integration, absence of inflammatory reaction (as revealed by myeloperoxidase staining) and increased vascularisation (by counting microvascular density following CD31 staining). Laser Doppler analysis revealed a statistically significant increase in blood flow after 1 week for PEG-EMD and after 2 weeks for PEG-NBG. The angiogenic response was significantly increased at 1, 2, and 8 weeks for PEG-EMD, but only at 4 weeks for PEG-NBG. Conclusions: The studied biomaterials revealed equal biocompatibility and tissue integration properties. PEG-EMD showed the most pronounced and consistent angiogenic response in the early phases of wound healing, while the PEG-NBG formulation provided a slower and delayed, but relevant, response.