Feeder Cells Free Rabbit Oral Mucosa Epithelial Cell Sheet Engineering

Generation of a novel model of bioengineered human oral mucosa with increased vascularization potential

Objective

The aim of this study was to generate novel models of bioartificial human oral mucosa with increased vascularization potential for future use as an advanced therapies medicinal product, by using different vascular and mesenchymal stem cell sources.

Background

Oral mucosa substitutes could contribute to the clinical treatment of complex diseases affecting the oral cavity. Although several models of artificial oral mucosa have been described, biointegration is a major issue that could be favored by the generation of novel substitutes with increased vascularization potential once grafted in vivo.

Methods

Three types of mesenchymal stem cells (MSCs) were obtained from adipose tissue, bone marrow, and dental pulp, and their in vitro potential was evaluated by inducing differentiation to the endothelial lineage using conditioning media. Then, 3D models of human artificial oral mucosa were generated using biocompatible fibrin‐agarose biomaterials combined with human oral mucosa fibroblasts and each type of MSC before and after induction to the endothelial lineage, using human umbilical vein endothelial cells (HUVEC) as controls. The vascularization potential of each oral mucosa substitute was assessed in vitro and in vivo in nude mice.

Results

In vitro induction of MSCs kept in culture was able to increase the expression of VEGF, CD31, and vWF endothelial markers, especially in bone marrow and dental pulp‐MSCs, and numerous proteins with a role in vasculogenesis become overexpressed. Then, in vivo grafting resulted in a significant increase in blood vessels formation at the interface area between the graft and the host tissues, with significantly positive expression of VEGF, CD31, vWF, and CD34 as compared to negative controls, especially when pre‐differentiated MSCs derived from bone marrow and dental pulp were used. In addition, a significantly higher number of cells committed to the endothelial lineage expressing the same endothelial markers were found within the bioartificial tissue.

Conclusion

Our results suggest that the use of pre‐differentiated MSCs could contribute to a rapid generation of a vascular network that may favor in vivo biointegration of bioengineered human oral mucosa substitutes.

The apoptotic and autophagic effects of cast Au-Pt, and differently manufactured Co-Cr and cp-Ti on three-dimensional oral mucosal model

The application of digitally manufactured dental metals has aroused the attention on their biocompatibilities. Three-dimensional oral mucosal model (3D OMM) would provide excellent assessments to the biocompatibility. In the current study, we set to measure metal ion release levels in the extracts of cast gold-platinum alloy (Au-Pt), differently manufactured cobalt-chromium alloy (Co-Cr) and commercially pure titanium (cp-Ti). We further tested two scaffold materials of 3D OMM to determine the better one for the succedent work. Lastly, we evaluated the apoptotic and autophagic effects of cast Au-Pt, and differently manufactured Co-Cr and cp-Ti on mucosal cells based on 3D OMM. We found that, in the construction of 3D OMM, Matrigel showed better performance than bovine acellular dermal matrix. Thus, Matrigel was chosen to construct the 3D OMM in the succedent studies. The results of ion release and biological assessments showed that, firstly, cast Au-Pt and cp-Ti triggered less early apoptotic cells and ion release than cast Co-Cr, implying better chemical stability and biocompatibility of them; secondly, digitally manufactured (including CAD/CAM milling and SLM) Co-Cr showed significantly lower ion release levels and lesser early apoptotic effects on 3D OMM as compared to the cast one. Although cast cp-Ti released much more ions than CAD/CAM milling one, manufacturing methods had no impact on apoptotic effect of cp-Ti. Therefore, we believe that digital methods possess same or even better chemical stability and biocompatibility than conventional casting one. Thirdly, although increased autophagic levels are observed in all test groups, so far there is no evidence that the test metals trigger different levels of autophagy as compared to each other. In addition, correlation analysis indicates that Co, W, and Mn appear to be the potential inducements for the apoptotic and autophagic effects of Co-Cr.

Recent update on craniofacial tissue engineering

The craniofacial region consists of several different tissue types. These tissues are quite commonly affected by traumatic/pathologic tissue loss which has so far been traditionally treated by grafting procedures. With the complications and drawbacks of grafting procedures, the emerging field of regenerative medicine has proved potential. Tissue engineering advancements and the application in the craniofacial region is quickly gaining momentum although most research is still at early in vitro/in vivo stages. We aim to provide an overview on where research stands now in tissue engineering of craniofacial tissue; namely bone, cartilage muscle, skin, periodontal ligament, and mucosa. Abstracts and full-text English articles discussing techniques used for tissue engineering/regeneration of these tissue types were summarized in this article. The future perspectives and how current technological advancements and different material applications are enhancing tissue engineering procedures are also highlighted. Clinically, patients with craniofacial defects need hybrid reconstruction techniques to overcome the complexity of these defects. Cost-effectiveness and cost-efficiency are also required in such defects. The results of the studies covered in this review confirm the potential of craniofacial tissue engineering strategies as an alternative to avoid the problems of currently employed techniques. Furthermore, 3D printing advances may allow for fabrication of patient-specific tissue engineered constructs which should improve post-operative esthetic results of reconstruction. There are on the other hand still many challenges that clearly require further research in order to catch up with engineering of other parts of the human body.

Clinical Trials of Limbal Stem Cell Deficiency Treated with Oral Mucosal Epithelial Cells

The corneal surface is an essential organ necessary for vision, and its clarity must be maintained. The corneal epithelium is renewed by limbal stem cells, located in the limbus and in palisades of Vogt. Palisades of Vogt maintain the clearness of the corneal epithelium by blocking the growth of conjunctival epithelium and the invasion of blood vessels over the cornea. The limbal region can be damaged by chemical burns, physical damage (e.g., by contact lenses), congenital disease, chronic inflammation, or limbal surgeries. The degree of limbus damage is associated with the degree of limbal stem cells deficiency (partial or total). For a long time, the only treatment to restore vision was grafting part of the healthy cornea from the other eye of the patient or by transplanting a cornea from cadavers. The regenerative medicine and stem cell therapies have been applied to restore normal vision using different methodologies. The source of stem cells varies from embryonic stem cells, mesenchymal stem cells, to induced pluripotent stem cells. This review focuses on the use of oral mucosa epithelial stem cells and their use in engineering cell sheets to treat limbal stem cell deficient patients.

Tissue Regeneration of Human Mesenchymal Stem Cells on Porous Gelatin Micro-Carriers by Long-Term Dynamic In Vitro Culture

Background

Tissue engineering is a multidisciplinary field which attracted much attention in recent years. One of the most important issue in tissue engineering is how to obtain high cell numbers and tissue regeneration while maintaining appropriate cellular characteristics in vitro for restoring damaged or dysfunctional body tissues and organs. These demands can be achieved by the use of three dimensional (3D) dynamic cultures of cells combined with cell-adhesive micro-carriers.

Method

In this study, human mesenchymal stem cells (hMSCs) were cultured in a wave-bioreactor system for up to 100 days, after seeding on Cultisphere-S porous gelatin micro-carriers. Cell counting was performed at the time points of 7, 12, 17, 31 days and compared to those of hMSCs cultured under static condition. Higher growth and proliferation rates was achieved in wave-type dynamic culture, when cell culture continued to day 31. A scanning electron microscope (SEM) photographs, both live and dead and MTT assays were taken to confirm the survival and distribution of cells on porous gelatin micro-carrier surfaces. The results of histological stains such as hematoxylin and eosin, Masson's trichrome, Alcian blue and Alizarin red S also showed improved proliferation and tissue regeneration of hMSCs on porous gelatin micro-carriers.

Conclusion

The experimental results demonstrated the effect and importance of both micro-carriers and bioreactor in hMSC expansion on cell proliferation and migration as well as extracellular matrix formation on the superficial and pore surfaces of the porous gelatin micro-carriers, and then their inter-connections, leading to tissue regeneration.