The Effect of Pulsed Electromagnetic Field Exposure on Fracture Healing Through the Wnt Signal Pathway

Abstract

Pulsed Electromagnetic Fields (PEMF) is reported to encourage the healing of nonunion fractures. However, the mechanism by which this occurs is still not known. Wnt signaling pathways are believed to be important signaling pathways in bone formation. This study will evaluate the healing of delayed union femur fracture, given PEMF exposure. 48 Spraque Dawley rats were fracturized at the left femoral shaft. These rats were randomized into two groups: A control group (24 rats) and the PEMF group (24 rats). The PEMF group was given PEMF exposure of 1.6 mT, with a frequency of 50 Hz for 4 h every day for 5, 10, 18 and 28 days, while the control group was not given PEMF exposure. Consequently, on days 5, 10, 18 and 28 days after fracture, 6 rats from each group were sacrificed. Callus bone was used for histological and RT-PCR examination on the expression of Wnt10b, Wnt5a and β-catenin. Blood samples were taken to examine Alkaline Phosphatase (ALP) activity using the ELISA method. Hematoxylin Eosin (HE) staining results showed that in the initial phase of healing, fibrous tissue in the fracture gap of the PEMF group was less compared to the control group. In the PEMF group, ALP activity increased significantly on day 10. This is thought to be related to an increase in osteoblast activity in a bone matrix formation. Furthermore, RT-PCR examination results showed that Wnt10b, Wnt5a and β-catenin gene expression was higher in the PEMF group compared to the control group. It can be concluded that PEMF exposure is thought to accelerate delayed union fracture healing through the Wnt signal pathway.

Histological Analysis of Bone Callus in Delayed Union Model Fracture Healing Stimulated with Pulsed Electromagnetic Fields (PEMF)

“…These results are consistent with molecular examinations of β -catenin expression conducted in previous studies. The highest β -catenin expression occurred on day 18 after fracture [ 17 ]. The expression of β -catenin in hypertrophic chondrocytes encourages the expression of osteopontin, which is the primary matrix protein in cartilage and bone [ 18 , 19 ].…”

“…Moreover, on the 28 th day, decreased β -catenin expression was observed. A decrease in β -catenin expression plays a role in encouraging preosteoclasts differentiation into mature osteoclasts that will absorb bone [ 17 ]. In previous studies, based on molecular analysis, an increase in the expression of RANK, RANKL, and OPG in the PEMF group was observed.…”

“…Until now, the molecular mechanism underlying PEMF fracture healing promotion is still being investigated. A signaling pathway may be involved in the Wnt signaling pathway [ 17 ].…”