Early Healing of Oral Soft Tissues: a Clinical and Biomolecular Analysis. Part I

Early Healing of Oral Soft Tissues: a Clinical and Biomolecular Analysis Part I - Gene Expression and Cellular Behaviour 24-hours After Injury

The purpose of the present study is to observe and compare -through a biomolecular analysis- the differences in the gene expression and cellular behavior in the early wound healing process -24 hours after injury- between the following three oral tissues: alveolar mucosa, buccal gingiva and palatal tissue. The main hypothesis is that there is a difference in the gene expression and in the cellular behaviour between the three oral tissues studied and this difference can be observed at 24 hours post-injury.

The wound healing is an extremely complex process. It has been observed that oral wounds mechanisms present special features. In fact, mucosal wounds demonstrated accelerated healing compared to cutaneous wounds. Numerous comparative studies have described important differences of cellular behavior and genes expression between oral mucosal and dermal tissues. Moreover, it has been observed that the behavior of the cells is autonomous, i.e., that greatest differences seen in the genomic response after injury in skin and mucosa are derived, in part, from intrinsic differences in the genetic regulation of the cells at each site. Also, it is important to highlight the fact that it has been observed that the cellular response after wound is early, showing the first and greatest changes at 12-24 hours post injury. Moreover, a recent study has been raised the possibility of that the transcriptional regulatory networks responsible for the accelerated healing in oral mucosa are already present in the unwounded state. In the oral mucosal tissues, the mechanisms underlying scar-less wound healing have been studied. Most studies have focused on the cellular characteristics and the molecular expression as growing factors, inflammatory mediators, etc., and have evaluated the process in later periods. Therefore, while the biomolecular basis of the differences in oral mucosal and dermal tissues wound healing have been described, this is less well understood in the different oral soft tissue wounds. The following points must be considered: The differences in the wound healing between mucosal and dermal tissues have been extensively studied through biomolecular analysis. The behavior of the cells is autonomous. The changes in the wound healing have been observed after 12-24 hours post-injury. The transcriptional regulatory networks responsible for the accelerated healing in oral mucosa could already be present in the unwounded state. The differences in the wound healing between the different oral soft tissues (alveolar mucosa, buccal gingiva and palatal tissue) has not been studied from a biomolecular point of view; however, differences in the clinical behavior and response between these three oral tissues has been reported. The main questions are: Twenty-four hours after injury: Are there differences in the gene expression and cellular behaviour between the three studied tissues? The transcriptional regulatory networks responsible for the accelerated oral tissues healing: Are presents in the unwounded state? Are differences between the three studied oral tissues? Deepen the knowledge in the early wound healing process of these tissues and the difference between them -evaluating the genes expression and the behavior of the cells- could allow the generation of new approaches to improve the healing of oral wounds.

Oral soft tissues biopsies (alveolar mucosa, buccal gingiva, and palatal tissue) will be harvested by the examiner at the time of the surgery (immediately before to start the surgical procedure -T0) and 24 hours after surgery (T24) at the level of the vertical released incisions (VRIs) with a biopsy punch with plunger of 2.0 mm diameter.

Total RNA from biopsies or cell cultures was extracted using TRIzol reagent Quantitative real-time PCR (qRT-PCR) cDNA was generated and cDNA obtained were used for amplification of wound healing related genes using the appropriate TaqMan gene expression assay kits.

Assessed with a clinical index (EHS- Early wound healing score). This score assessed clinical signs of re-epithelialization (CSR), clinical signs of haemostasis (CSH), and clinical signs of inflammation (CSI). Since complete wound epithelialization was the main outcome, the CSR score was weighted to be 60% of the total final score. Accordingly, a score of 0, 3, or 6 points was possible for the assessment of CSR, whereas scores of 0, 1, or 2 points were possible for CSH and CSI. Higher values indicated better healing. Accordingly, the score for ideal early wound healing was 10.

Inclusion Criteria: patients that required periodontal surgery; patients age between 30-60 years; patients with full mouth plaque score and full mouth bleeding score < 15%; patients with a good general healthy status; patients without any medicaments or drug consumption that can affect the healing process; non-smoking patients. Exclusion Criteria: patients in pregnancy; patients in lactation period; patients with consumption of antibiotics or anti-inflammatory drugs in the previous six months; patients with systemic diseases.

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