Exploring the role of MicroRNA-200a in mandibular condylar cartilage growth following functional appliance therapy in growing children: A pilot study

Introduction: Functional appliance therapy (FAT) in orthodontics brings about mandibular growth in children with retrognathic/short mandible. But, to date its effectiveness in resultant condylar growth at cellular and molecular level has not been studied. Thus, the current pilot study aimed to study non-coding microRNA-200a, which is a known marker of embryonic cartilage development, in saliva and serum of such patients to understand the adaptive condylar growth. Materials and Methods: Biofluid samples were collected from 5 growing patients (boys and girls, 9-11 years) undergoing FAT at two observation times: T0(pre-FAT) and T1(9 months post-FAT). The samples underwent total RNA extraction and purification according to the manufacturer’s instructions. RNA was reverse transcribed followed by cDNA synthesis, and miRNA quantification using has-mir-200a forward primer. Samples were analyzed in duplicate using the ΔCt (cycle threshold value). The differences in ΔCt pre and post-FAT were statistically analysed using Wilcoxon signed-rank test. Results: MiR200a was present in all blood and saliva samples, but varied in detection. There was no significant difference between the pre-FAT and post-FAT salivary ΔCt values (Z=-0.405, p=0.686), and serum ΔCt values (Z=-0.365, p=0.715). The Spearman Rho correlation between ΔCt pre-FAT and post-FAT for both saliva and serum shows a good negative correlation but is non-significant. Bioinformatics revealed that hsa-miR-200a-3p plays a role in cartilage development by regulating target genes, including TFAP2C, KLF6, NR3C1, CALCR, and YTHDF2. Conclusions: MiRNA-200a may be an important biomarker for cartilaginous growth in response to FAT. Its presence in saliva highlights non-invasive diagnostic potential and can be explored further for personalized treatments.