ABSTRACT
Current diagnostic tools are neither informative of, nor concurrent with the underlying biological processes of fracture healing. We examined if there would be protein markers in the plasma of non-operatively fixed, isolated, non-articular, humeral fractures that would be informative of these biological processes. Five follow-up visits over a six-month period were examined in 24 patients that healed (union) and 7 non-healers (nonunion). Using the first or last clinic visit as the reference, 118 proteins out of ∼7000 proteins that were assayed, showed differential expression at log2 fold change ≥1.3 fold and a significance of FDR ≤ 0.5. Multiple proteins related to endochondral bone development showed significant increased plasma levels during the first 12-16 weeks. Proteins associated with acute phase response, inflammation and lipid storage showed decreased levels after their initial induction. Using a time point to time point comparison for the first three follow-up visits (up to 9 weeks after injury) between healed and nonunion patients, identified 41 proteins with differential levels at p ≤ 0.05 significance, with ten overlapping the 118 proteins that tracked normal healing. The differential group associated with the nonunion patient‘s included specific extracellular matrix and acute phase proteins that showed decreased levels relative to normal healers. These data establish the progression of endochondral bone formation and place them in context to radiological and functional outcomes in human fracture healing. The identification of differentially expressed proteins in nonunion plasma suggests the potential for the development of diagnostic markers for the early intervention of nonunion.
ClinicalTrials.gov#NCT05143476
Sponsor/Funding Source DOD W81XWH-19-1-0796
Competing Interest Statement
The authors have declared no competing interest.
Funding Statement
Name of the Funder: Department of Defense (DoD) Grant Number: W81XWH-19-1-0796 Recipient Author: Louis Gerstenfeld, PhD
Author Declarations
I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.
Yes
The details of the IRB/oversight body that provided approval or exemption for the research described are given below:
This study was carried out under Johns Hopkins University School of Medicine (JHU SOM) single Institutional Review Board (sIRB) approved protocol administered by Major Extremity Trauma Research Consortium (METRC) Coordinating Center (MCC) at Johns Hopkins University Bloomberg School of Public Health (JHSPH). The protocol (IRB00237830) was originally approved on November 3, 2020, with current expiration date of April 20, 2026.
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Footnotes
Conflict of Interest: The authors have declared that no conflict of interest exists.
Data Availability
All data produced in the present study are available upon reasonable request to the authors
