Effect of intranasal administration of concentrated growth factors on regeneration of the olfactory epithelium in an olfactory dysfunction-induced rat model

Objective The development of treatments that promote the regenerative capacity of the olfactory epithelium (OE) is desirable. This study aimed to evaluate the effects of intranasal administration of concentrated growth factors (CGFs) in a rat model of olfactory dysfunction. Study design Animal study. Methods Nineteen male rats were used. Fourteen olfactory dysfunction models were created by intraperitoneal administration of 3-methylindole. We randomly divided the rats from the olfactory dysfunction model after 1 week into the CGF or saline group; CGFs were administered to seven animals and saline to seven animals. Behavioral assessments using the avoidance test were conducted until day 28 after CGF/saline administration. On day 28, histological evaluation was conducted to determine olfactory epithelial thickness and the olfactory marker protein (OMP)-positive cell count. Five animals were intraperitoneally injected with saline as the control group. Results The avoidance rate remained decreased until 28 days after CGF/saline administration, and there was no significant difference between the two groups. Olfactory epithelial thicknesses on day 28 were 38.64 3.17 mu m and 32.84 +/- 4.50 mu m in the CGF and saline groups, respectively. OE thickness was significantly thicker in the CGF group than in the saline group (P = 0.013). The numbers of OMP-positive cells were 40.29 +/- 9.77/1.0 x 10(4)mu m(2) and 31.00 +/- 3.69/1.0 x 10(4) mu m(2) in the CGF and saline groups, respectively. The number of OMP+ cells in the CGF group was significantly increased compared with that in the saline group (P = 0.009). Both groups showed no improvement compared with the control group (OE thickness: 54.08 +/- 3.36 mu m; OMP+ cell count: 56.90 +/- 9.91/1.0 x 104 mu m(2)). Conclusions The CGF group showed improved olfactory epithelial thickness and OMP-positive cell numbers compared with that in the saline group.