Objectives: In order to ensure improved and accelerated bone regeneration, nano-hydroxyapatite scaffolds are often enriched with different bioactive components to further accelerate and improve bone healing. In this review, we critically examined whether the enrichment of nHAp/polymer scaffolds with growth factors, hormones, polypeptides, microRNAs and exosomes improved new bone formation in vivo. Materials and Methods: Out of 2989 articles obtained from the literature search, 106 papers were read in full, and only 12 articles met the inclusion criteria for this review. Results: Several bioactive components were reported to stimulate accelerated bone regeneration in a variety of bone defect models, showing better results than bone grafting with nHAp scaffolds alone. Conclusions: The results indicated that composite materials based on nHAp are excellent candidates as bone substitutes, while nHAp scaffold enrichment further accelerates bone regeneration. The standardization of animal models should be provided in order to clearly define the most significant parameters of in vivo studies. Only in this way can the adequate comparison of findings from different in vivo studies be possible, further advancing our knowledge on bone regeneration and enabling its translation to clinical settings.

Oral microbiome disruptions in periodontitis are related to the chronic inflammatory reactions that could in turn lead to the development of multiple oral diseases. The objective of the study was to assess the frequencies of Streptococcus mitis, Prevotella melaninogenica, and Prevotella intermedia in oral benign lesions, oral potentially malignant disorders (OPMDs), and oral squamous cell carcinomas (OSCCs) and investigate the impact of these bacteria on the expression patterns of the selected (potential) target genes (PI3CA/AKT2/mTOR, DUSP16/MAPK14, and COX2). After sample collection (25 benign lesions, 30 OPMDs, and 35 OSCCs) and DNA/RNA extraction, quantitative real-time polymerase chain reaction (qPCR) was performed to detect bacterial presence and assess relative gene expression levels in different lesion groups. Prevotella melaninogenica was the most prevalent of the three analyzed bacteria, with the frequency being 60% in benign lesions, 87% in OPMDs (p = 0.024), and 77% in OSCC. The OPMD tissues in which Prevotella melaninogenica was present exhibited a higher expression level of AKT2 (p = 0.042). Significantly lower expression of DUSP16 was observed in OSCC tissues containing Streptococcus mitis (p = 0.011). The obtained results indicate a substantial contribution of P. melaninogenica and Str. mitis in the pathogenesis of oral mucosal lesions, possibly via AKT2 upregulation and DUSP16 downregulation.

Exosomes, small extracellular vesicles secreted by various cell types, have gained significant attention in cancer investigations. Isolation and characterization of exosomes derived from DOK (dysplastic oral keratinocyte), SCC (squamous cell carcinoma) and HaCaT (normal skin keratinocyte) cell lines and microRNA profiling were conducted. Magnetic sorting was applied to obtain pure exosomes. Morphology and size were characterized by transmission electron microscopy and nanoparticle tracking analysis. Validation of membrane exosomal markers (CD9, CD63) was performed via Western blotting. MiR-21, miR-31, and miR-133 levels were analyzed in exosomes and parent cells by qPCR. Biological effects of the exosomes were tested by adding them to fibroblast cultures and determining the expression of relevant carcinogenesis markers by qPCR. Exosomes appeared as cup-shaped nano-sized particles, and there was no difference regarding particle diameter and concentration between the three types of exosomes. The oncogenic miR-21 was significantly upregulated both in SCC and SCC-derived exosomes compared to DOK and HaCaT cells and their respective exosomes. However, miR-31 unexpectedly showed the highest expression in normal cells and the lowest in HaCaT exosomes. MiR-133, the tumor suppressor miRNA, was downregulated in both SCC and DOK cells compared to normal (HaCaT) cells, while the opposite situation was observed in exosomes, with HaCaT cells showing the lowest levels of miR-133. The differences in exosome content were reflected in signaling pathway activation in exosome-treated fibroblasts, with SCC exosomes exerting the most potent effect on several cancer-related pathways, notably PIK3/AKT, PTEN, and NOTCH signaling cascades.

The aim of the present systematic review was to critically analyse the relationship between tumour suppressor genes (TSGs) promoter methylation, a potent mechanism of gene silencing, and the development of salivary gland tumours, as well as the possible effect on clinical/histological characteristics. Review protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (registration ID CRD42020218511). A comprehensive search of Web of Science, Scopus, PubMed, and Cochrane Central Register of Controlled Trials was performed utilizing relevant key terms, supplemented by a search of grey literature. Newcastle-Ottawa Quality Assessment Scale (NOQAS) was used for the quality assessment of included studies. Sixteen cross-sectional and 12 case-control studies were included in the review, predominantly dealing with methylation in TSGs related to DNA repair, cell cycle, and cell growth regulation and differentiation. Quantitative synthesis could be performed on P16 (inhibitor of cyclin-dependent kinase 4a), RASSF1A (Ras association domain family 1 isoform A) and MGMT (O6-methylguanine DNA methyltransferase) genes only. It showed that P16 and RASSF1A genes were more frequently methylated in salivary gland tumours compared to controls (P = .0002 and P < .0001, respectively), while no significant difference was observed for MGMT. Additionally, P16 did not appear to be related to malignant transformation of pleomorphic adenomas (P = .330). In conclusion, TSG methylation is involved in salivary gland tumour pathogenesis and several genes might play a considerable role. Further studies are needed for a better understanding of complex epigenetic deregulation during salivary gland tumour development and progression.