Effect of cell sheet of human dental pulp stem cell, associated or not with photobiomodulation therapy, on the repair of critical size bone defects in calvaria of rats with Type 2 Diabetes Mellitus

Author(s)

Ana Clara Fagundes Pedroni

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia (FO/SDO)
• Defense date: 2020-05-27

Examining board members

Marcia Martins Marques; Luciana Corrêa; Fernanda de Paula Eduardo; Maria Stella Nunes Araujo Moreira

• Advisor: Marcia Martins Marques

Abstract

Diabetes Mellitus (DM) is a metabolic disorder that compromises bone repair, requiring new therapeutic strategies. One of them is based on the application of cell therapy through the use of \"Cell sheet\" (CS) cultures - which preserve cell-cell contact, the structural organization and the phenotype of stem cells (CTs). Another alternative treatment is photobiomodulation therapy (PBMT), which induces responses that favor tissue regeneration. The aim of this study was to evaluate the effect of the use of CSs from undifferentiated human dental pulp (hDPSC4), associated or not with PBMT, in the bone repair of lesions in calvaria of diabetic rats. The study comprises two stages: one in vitro (obtaining and characterizing the CSs) and one in vivo. First, DM was induced in 54 rats, by the administration of Streptozotocin. Bone lesions were performed on the parietal bones of all animals. These injuries were treated according to the six experimental groups (n = 6 per group / experimental time) - G.Control: injury without treatment; G.PBMT: lesion treated with PBMT; G.MCol: placement of commercial porcine collagen membrane; G.MCol+PBMT: placement of the porcine collagen membrane followed by the application of PBMT; G.CS: placement of CS and G.CS+PBMT: placement of CS followed by PBMT. PBMT was performed using an infrared laser (808 nm, 40 mW, 0.028 cm2 of beam area, 1.4 W/cm2, 3 s, 4 J/cm2, 0.12 J per point) immediately, 48 and 96 hours after the surgery. Thirty and 60 days after surgery, the skull caps were dissected, fixed and submitted to the analysis of: Computed Microtomography (MicroCT), histology (HE) and histochemistry (Masson\'s Trichrome). The data were treated statistically (p<=0.05). Undifferentiated DPSC CS did not accelerate the bone repair process in most lesions, with abundant bone formation in only two animals from G.CS+PBMT in 60 days. MicroCT revealed, in 60 days, a significant increase in relative bone volume (p=0.0064) and number of trabeculae (p=0.0068) in the G.MCol+PBMT group and in relative bone volume (p<0.0001) and trabecula thickness (p<0.0001) in the G.PBMT group. Histologically, it was possible to observe that CS, in 30 days, promoted the formation of organized osteoid tissue, rich in collagen fibers and osteoblastic cells, with formation of islets of bone neoformation distant from the edges of the lesion. However, this new formation was considered immature when compared to the other groups. When CS was associated with PBMT, it was possible to observe more collagen fibers and a greater frequency of islets in the center of the lesion. In the experimental conditions of this research, in most cases, the undifferentiated hDPSC4 cell sheet (CS) was not able to accelerate the process of repairing critical bone lesions in diabetic rat calvaria. (AU)

• FAPESP's process: 17/00760-6 - Effect of Cell Sheet of human dental pulp stem cell, associated or not with photobiomodulation therapy, on the regeneration of critical size bone defects in calvaria of rats with Type 2 Diabetes Mellitus
• Grantee: Ana Clara Fagundes Pedroni
• Support Opportunities: Scholarships in Brazil - Doctorate