Extracellular vesicles as a novel therapeutic tool for cell-free regenerative medicine in oral rehabilitation

Oral maxillofacial defects may always lead to complicated hard and soft tissue loss, including bone, nerve, blood vessels, teeth and skin, which are difficult to restore and severely influence the life quality of patients. Extracellular vesicles (EVs), including exosomes, microvesicles and apoptotic bodies, are emerging as potential solutions for complex tissue regeneration through cell-free therapies. In this review, we highlight the functional roles of EVs in the regenerative medicine for oral maxillofacial rehabilitation, specifically bone, skin, blood vessels, peripheral nerve and tooth-related tissue regeneration. Publications were reviewed by two researchers independently basing on three databases (PubMed, MEDLINE and Web of Science), until 31 December 2018. Basing on current researches, we classified the origin of EVs for regenerative medicine into four categories: related cells in the regenerative niche, mesenchymal stem cells, immune cells and body fluids. The secretome of different cells are distinct, while the same cells secrete different EVs under varied conditions; therefore, the content profiles of EVs and regulatory mechanisms on target cells are compared and emphasised. By unravelling the regulatory mechanisms of EVs in tissue regeneration, modified cells and tailored EVs with specific target may be produced for precision medicine with high efficacy.     

Exosomes and other extracellular vesicles in oral and salivary gland cancers

Extracellular vesicles (EVs, including exosomes) are a group of heterogeneous nanometer‐sized vesicles that are released by all types of cells and serve as functional mediators of cell‐to‐cell communication. This ability is primarily due to their capacity to package and transport various proteins, lipids, and nucleic acids—namely DNA and messenger RNA (mRNA), but also microRNAs (miRNAs) and long non‐coding RNAs (lncRNAs). These contents can influence the function and fate of both recipient and donor cells. More and more studies have shown that EVs are involved in every phase of cancer development, mediating bidirectional cross talk between cancer cells and their tissue microenvironment. More specifically, EVs can promote tumor progression by modifying vesicular contents and establishing a distant premetastatic niche with molecules that favor cancer cell proliferation, migration, invasion, metastasis, angiogenesis, and even drug resistance. Given that the packaging of these molecules is known to be tissue‐specific, EVs can not only serve as novel prognostic and diagnostic markers but also be used as potential therapeutic targets and vehicles for drug delivery. The present review discusses the current understanding of the multifaceted roles of EVs in the progression of oral and salivary gland cancers, as well as their potential use in clinical applications.     

Role of angiogenic and non-angiogenic mechanisms in oral squamous cell carcinoma: correlation with histologic differentiation and tumor progression

BACKGROUND: Angiogenesis has been demonstrated to associate with various measures of tumor aggressiveness in many human malignancies. However, studies of tumor angiogenesis in oral squamous cell carcinoma (SCC) are still unclear. Recent studies indicate non-angiogenesis mechanism (tumor-lined vessel) may exist in certain tumors. Therefore, we investigate microvessel density (MVD) and tumor-lined vessel in oral SCC. METHODS: Peritumoral and intratumoral MVD were measured by immunohistochemical staining. Tumor-lined vessels were identified by double staining. Statistical analysis of peritumoral and intratumoral MVD and presence of tumor-lined vessels with clinicopathologic parameters was performed. RESULTS: The results showed peritumoral MVD increased with disease progression and further increases of intratumoral MVD was detected by CD31 and CD34. Non-angiogenesis, tumor-lined vessel, presented in oral SCC and correlated significantly with tumor size, stage, and histologic differentiation. CONCLUSION: Our results suggest at the initiation of oral SCC, increasing vascularity is observed at the periphery of the tumor. As the tumor continues to grow, further increases of intratumoral vascularity and the presence of tumor-lined vessels are associated with cancer progression.     

The role of cyclin‐dependent kinases in oral potentially malignant disorders and oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a major global health problem with a relatively low‐moderate 5‐year survival rate. OSCC is often preceded by lesions and conditions known as oral potentially malignant disorders (OPMDs) that have an increased risk of malignant transformation. Despite advances in diagnostic technology and cancer research, the prognosis of OSCC remains poor as it is frequently detected a late stage. Understanding the molecular pathways involved in oral carcinogenesis provides a platform to identify biomarkers that may allow the early detection of OSCC and accurate prediction of the malignant potential of OPMDs. In addition, specific molecular inhibitors can be developed to target these important pathways and allow advanced therapeutic management to improve the prognosis of this malignancy. A common feature across a number of different cancers is the dysfunction of cell cycle moderator proteins known as cyclin‐dependent kinases. This review summarises the current literature regarding the role of cyclin‐dependent kinases in oral carcinogenesis with a particular focus on cyclin‐dependent kinases 4 (CDK4) and 6 (CDK6). This is of particular relevance as CDK4 and CDK6 inhibitors have shown some promising results in other cancer types and are interesting potential treatments for OSCC.     

Increase of mast cells and tumor angiogenesis in oral squamous cell carcinoma

BACKGROUND: Although mast cells (MCs) have been implicated in promoting angiogenesis in some malignant tumors, especially of the aerodigestive tract, little is known in oral squamous cell carcinoma (SCC). METHODS: A retrospective study was conducted to elaborate upon the correlation between MCs and tumor angiogenesis in 26 cases of oral SCC, six cases of oral pre-malignant dysplasia, 10 cases of oral hyperkeratosis, and six cases of normal oral mucosa by means of immunohistochemical technique. RESULTS: The MCs in all lesions and normal oral mucosa strongly expressed tryptase. The densities of MCs and microvessels appeared to increase with disease progression. The MC and microvascular counts were significantly higher in oral SCC than in hyperkeratosis and normal oral mucosa (P < 0.05). A significant correlation between MC and microvascular densities was observed in oral SCC (r = 0.5; P = 0.012). CONCLUSIONS: These findings suggest that MCs may upregulate tumor angiogenesis in oral SCC, perhaps via MC tryptase.     

Significance of myofibroblasts in oral squamous cell carcinoma

J Oral Pathol Med (2011) 40 : 201–207 It is now recognized that the tumor microenvironment makes significant contribution to tumor progression. Activated fibroblast endothelial cells, inflammatory cells, and various extra cellular matrix components are parts of this microenvironment. Most of the activated fibroblasts are α‐smooth muscle actin–positive myofibroblast that often represent the majority of tumor stromal cells. Their production of growth factors chemokines and extracellular matrix facilitates tumor growth. Myofibroblast have been demonstrated in close to 50% of oral squamous cell carcinomas. In this review, we highlight the histological distribution of myofibroblast in oral squamous cell and the myofibroblast relation to tumor growth on prognosis.     

Cytomorphometric analysis of squames obtained from normal oral mucosa and lesions of oral leukoplakia and squamous cell carcinoma

Ramaesh T, Mendis BRRN, Ratnatunga N, Thattil RQ: Cytomorphometric analysis of squames obtained from normal oral mucosa and lesions of oral leukoplakia and squamous cell carcinoma. J Oral Pathol Med 1998; 27: 83–6. © Munksgaard, 1998.
Cell and nuclear diameters (CD and ND) were measured in squames obtained from normal buccal mucosa and lesions of oral leukoplakia and squamous carcinoma (SCC) also from buccal mucosa. The study groups consisted of Group 1: normal buccal mucosa ( n = 40); Group 2: lesions with no epithelial dysplasia ( n = 58); Group 3: lesions with epithelial dysplasia ( n = 27); and Group 4: SCC lesions ( n = 51). The mean CD and ND values were: Group 1: 51.78 (± 0.11) and 8.36 (± 0.49); Group 2: 45.73 (± 0.16) and 8.31(± 0.68); Group 3: 41.32 (± 0.13) and 9.04 (± 0.46); Group 4: 38.58 (± 0.11) and 10.10 (± 0.56) urn, respectively. Correlation between the ND and CD was positive for Group 1 ( r = 0.78, P < 0.05) and Group 2 ( r = 0.33, P < 0.05). There were no significant correlations in Groups 3 and 4. ANOVA showed significant differences ( P < 0.05) for CD between all four groups. Except between Groups 1 and 2, the ND was significantly different ( P < 0.05) between all groups. The results indicate that ND and CD could possibly be sensitive parameters in the diagnosis of oral premalignant and malignant lesions.     

Outcomes of oral squamous cell carcinoma arising from oral epithelial dysplasia: rationale for monitoring premalignant oral lesions in a multidisciplinary clinic

Surveillance of oral epithelial dysplasia results in a number of newly diagnosed cases of oral squamous cell carcinoma (SCC). The clinical stage of oral SCC at diagnosis influences the magnitude of treatment required and the prognosis. We aimed to document the stage, treatment, and outcome of oral SCC that arose in patients who were being monitored for oral epithelial dysplasia in a dedicated multidisciplinary clinic. Those with histologically diagnosed lesions were enrolled on an ethically approved protocol and molecular biomarker study. Details of clinical and pathological TNM, operation, radiotherapy, recurrence, second primary tumour, and prognosis, were recorded in patients whose lesions underwent malignant transformation. Of the 91 patients reviewed (median follow-up 48 months, IQR 18-96), 23 (25%) had malignant transformation. All were presented to the multidisciplinary team with stage 1 disease (cT1N0M0). Of these, 21 were initially treated by wide local excision, 2 required resection of tumour and reconstruction, and 2 required adjuvant radiotherapy. At follow-up 3 had local recurrence, one had regional recurrence, one had metachronous lung cancer, and 5 had second primary oral SCC. There were further diagnoses of oral dysplasia in 5 during follow-up, and it is estimated that 76% of patients will have one or other event in 5 years. Disease-specific survival was 100% and overall survival was 96% (22/23). Median follow-up after diagnosis of oral SCC was 24 months (IQR 11-58). Specialist monitoring of oral epithelial dysplasia by a multidisciplinary team allows oral SCC to be detected at an early stage, and enables largely curative treatment with simple and usually minor surgical intervention. The high incidence of second primary oral SCC in high-risk patients with oral epithelial dysplasia further supports intensive targeted surveillance in this group.