Evaluation of Prx1 expression during fracture healing in murine models
Embargo Date
2027-10-21
OA Version
Citation
Abstract
INTRODUCTION:Fracture repair is a complex process with the periosteum as the main source of stem and osteoprogenitor cells involved in fracture repair. In prior studies, Prx1 expression has been observed in the osteochondral progenitor cells. Thus, Prx1 has been used as a marker of periosteal stem/progenitor cells. However, Prx1 still requires further research to understand the spatial and temporal characteristics of this cell population.
AIMS: Characterize how the Prx1 cell population responds to fracture repair using quantitative real time polymerase chain reaction (qRT-PCR), flow cytometry, and histology.
METHODS: The relative expression of Prx1 mRNA was quantified by qRT-PCR fracture calluses mRNA and histology samples over the course of fracture repair (3-35 days). The dynamic expression of Prx1 expressing cell populations was determined using tamoxifen inducible transgenic mice, Prx1CreER-GFP/Ai14/Rag1. Fluorescence was used to quantify the cell population through flow cytometry.
RESULTS: Through qRT-PCR, relative expression of Prx1 was found to peak at postoperative day (POD) 3 and 7 with a minor peak at POD 18. Additionally, through flow cytometry the percentage of Prx1 (identified by dTomato) was determined to be 0.0145% at POD 3 and 0.41% at POD 7. Lastly, histology showed Prx1 positive cells to be in the outer callus periosteal surface at POD 7. While at POD 10 and 14 Prx1 expression appeared to be decreased and located in the inner callus surface.
CONCLUSION: The peak Prx1 expression at POD 7 reiterated previous fracture studies in mice.
Results from flow cytometry also seem to reiterate peak Prx1 expression at POD 7, although further time points should be included in a future study. Additionally, this study also appeared to show an increase in Prx1 positive cells in the contralateral limb, this seems to indicate a possible systemic expression of Prx1. However future studies should be done with a greater population size and longer timepoints. Lastly through histology it was shown that Prx1 positive cells at POD 7 are localized along the outer callus and the periosteum, seeming to confirm that the periosteum is a major source for stem cells involved in fracture healing. At later time points POD 10 and 14, Prx1 expression is seen in the inner callus. This change in localization is interesting, as it seems to show a secondary expression of Prx1 in the inner callus. Altogether Prx1 requires more research to fully understand its role in fracture repair.
Description
2024