Skin and oral mucosal substitutes

Recent trends and perspectives in reconstruction and regeneration of intra/extra-oral wounds using tissue-engineered oral mucosa equivalents

Many conditions, including cancer, trauma, and congenital anomalies, can damage the oral mucosa. Multiple cultures of oral mucosal cells have been used for biocompatibility tests and oral biology studies. In recent decades, the clinical translation of tissue-engineered products has progressed significantly in developing tangible therapies and inspiring advancements in medical science. However, the reconstruction of an intraoral mucosa defect remains a significant challenge. Despite the drawbacks of donor-site morbidity and limited tissue supply, the use of autologous oral mucosa remains the gold standard for oral mucosa reconstruction and repair. Tissue engineering offers a promising solution for repairing and reconstructing oral mucosa tissues. Cell- and scaffold-based tissue engineering approaches have been employed to treat various soft tissue defects, suggesting the potential clinical use of tissue-engineered oral mucosa (TEOMs). In this review, we first cover the recent trends in the reconstruction and regeneration of extra-/intra-oral wounds using TEOMs. Next, we describe the current status and challenges of TEOMs. Finally, future strategic approaches and potential technologies to support the advancement of TEOMs for clinical use are discussed.

Characterization of Mono- and Bi-Transgenic Pig-Derived Epidermal Keratinocytes Expressing Human FUT2 and GLA Genes-In Vitro Studies

Pig-to-human xenotransplantation seems to be the response to the contemporary shortage of tissue/organ donors. Unfortunately, the phylogenetic distance between pig and human implies hyperacute xenograft rejection. In this study, we tested the hypothesis that combining expression of human α1,2-fucosyltransferase (hFUT2) and α-galactosidase A (hGLA) genes would allow for removal of this obstacle in porcine transgenic epidermal keratinocytes (PEKs). We sought to determine not only the expression profiles of recombinant human α1,2-fucosyltransferase (rhα1,2-FT) and α-galactosidase A (rhα-Gal A) proteins, but also the relative abundance (RA) of Galα1→3Gal epitopes in the PEKs stemming from not only hFUT2 or hGLA single-transgenic and hFUT2×hGLA double-transgenic pigs. Our confocal microscopy and Western blotting analyses revealed that both rhα1,2-FT and rhα-Gal A enzymes were overabundantly expressed in respective transgenic PEK lines. Moreover, the semiquantitative levels of Galα1→3Gal epitope that were assessed by lectin fluorescence and lectin blotting were found to be significantly diminished in each variant of genetically modified PEK line as compared to those observed in the control nontransgenic PEKs. Notably, the bi-transgenic PEKs were characterized by significantly lessened (but still detectable) RAs of Galα1→3Gal epitopes as compared to those identified for both types of mono-transgenic PEK lines. Additionally, our current investigation showed that the coexpression of two protective transgenes gave rise to enhanced abrogation of Galα→3Gal epitopes in hFUT2×hGLA double-transgenic PEKs. To summarize, detailed estimation of semiquantitative profiles for human α-1,2-FT and α-Gal A proteins followed by identification of the extent of abrogating the abundance of Galα1→3Gal epitopes in the ex vivo expanded PEKs stemming from mono- and bi-transgenic pigs were found to be a sine qua non condition for efficiently ex situ protecting stable lines of skin-derived somatic cells inevitable in further studies. The latter is due to be focused on determining epigenomic reprogrammability of single- or double-transgenic cell nuclei inherited from adult cutaneous keratinocytes in porcine nuclear-transferred oocytes and corresponding cloned embryos. To our knowledge, this concept was shown to represent a completely new approach designed to generate and multiply genetically transformed pigs by somatic cell cloning for the needs of reconstructive medicine and dermoplasty-mediated tissue engineering of human integumentary system.

Collagen matrix membrane as a biological dressing in defects of the oral mucosa

OBJECTIVES

The objectives of this study were to evaluate the usefulness of the extracellular collagen matrix membrane as a biological wound dressing material for defects of the oral mucosa.

MATERIALS AND METHODS

One hundred two patients were included in the study. A bovine-based extracellular matrix collagen membrane was used. The study was confined to those defects of oral mucosa which were large enough to close primarily.

RESULTS

The results were evaluated under various parameters such as hemostasis, pain relief, granulation, epithelialization, and contracture of the wound. Secondary infection and allergenicity to the membrane were also considered, and finally, the usefulness of the collagen membrane was tested by the use of the Chi-square test and P < 0.001 was found.

CONCLUSION

We concluded that the extracellular collagen membrane could be used as a biological dressing in oral defects. Although it does not replace, it is proved as a good substitute of autologous graft.

Ex vivo culture of oral keratinocytes using direct explant cell culture technique

Background:

Culture of cells and tissues is a standard research method practiced in many laboratories. In most of the cases, these cultures are being used as substrates for cell products or as investigative tools for delving the mechanism of gene expression, cell proliferation and transformation. Primary monolayer cell culture has been beneficial to study the general biology of both oral and skin keratinocytes. There are two different techniques of primary cell cultures followed, which include direct explant and enzymatic techniques.

Aims:

The aim of the study was to optimize the culture of keratinocytes obtained from patients with normal oral mucosa by direct explant technique.

Materials and Methods:

Keratinocytes were isolated from 15 patients and were cultured in vitro and observed under an inverted microscope. The cultured cells were characterized by immunocytochemistry method using pan-cytokeratin.

Results:

The total success rate of primary culture of the oral epithelial cells by direct explant technique was 88.6%. No contamination of microorganisms in the primary cell cultures was obtained.

Conclusion:

Within the limited numbers of samples used in the current pilot study, we conclude that the direct explant technique appears to be a simple and successful technique for the isolation of oral mucosal keratinocytes if we follow the appropriate protocol.

Basic Principles of Bioengineering and Regeneration

In a quest to provide best-quality treatment, results, and long-term prognosis, physicians must be well versed in emerging sciences and discoveries to more favorably provide suitable options to patients. Bioengineering and regeneration have rapidly developed, and with them, the options afforded to surgeons are ever-expanding. Grafting techniques can be modified according to evolving knowledge. The basic principles of bioengineering are discussed in this article to provide a solid foundation for favorable treatment and a comprehensive understanding of the reasons why each particular treatment available can be the most adequate for each particular case.

[Oral mucosa analog allografts in non-consanguineous rats]

INTRODUCTION

Although there are therapeutic options for the treatment of oral mucosa defects, the need for functional, anatomical and aesthetically similar substitutes persists, as well as for solutions to reduce autologous grafts morbidity.

OBJECTIVE

To determine clinical and histological compatibility of equivalent oral mucosa allografts generated through tissue engineering in non-consanguineous rats.

MATERIALS AND METHODS

We used a sample of oral mucosa from Sprague Dawley rats to obtain a fibroblast culture and a keratinocytes and fibroblasts co-culture. In both cases, we used a commercial collagen membrane as "scaffold". After ten weeks of culture, we grafted the resulting membranes into four Wistar rats. The first phase of the study was the development of the oral mucosa equivalents generated by tissue engineering. Then, we implanted them in immunocompetent Wistar rats, and finallywe evaluated the clinical and histological features of the allografts.

RESULTS

In vivo evaluation of mucosal substitutes showed a correct integration of artificial oral mucosa in immunocompetent hosts, with an increase in periodontal biotype and the creation of a zone with increased keratinization. Histologically, the tissue was similar to the control oral mucosa sample with no inflammatory reaction nor clinical or histological rejection signs.

CONCLUSION

The equivalent oral mucosa allografts generated by tissue engineering showed clinical and histological compatibility.

Versitality of the Use of Collagen Membrane in Oral Cavity

INTRODUCTION

Bovine derived collagen membrane is usually and regularly used as a temporary cover or dressing for the extra oral wounds and for the burns on the body. It has wide applications because of its usefulness and biocompatibility. This has provoked us to do a study with the use of collagen membrane even for the intraoral minor surgical defects.

AIM

The study was conducted to evaluate the clinical efficacy of collagen membrane as a biological dressing material for intraoral wounds, to check for haemostasis, pain control, granulation tissue formation, rapid re-epithelialization and minimal contracture.

MATERIALS AND METHODS

A total of 30 patients 19 male, 11 female were taken for excision of various intraoral lesions like leukoplakia patches, mucocele, epulis growths, irritational fibroma, frenectomy and the surgical defects were closed with collagen membrane. Postoperatively healing was assessed by taking five clinical parameters of Haemostasis, Pain, Granulation tissue, Epithelialization, Contracture.

RESULTS

Among 30 patients, haemostasis score was found to be good in 28 cases, fair in two cases. Pain relief score was good in seven cases, fair in 19 cases, poor in four cases. Granulation tissue formation score was good in eight cases, fair in 13 cases, poor in nine cases. Epithelialization score was good in 19 cases, fair in seven cases, poor in four cases. Contracture score was good in six cases, fair in 16 cases, poor in eight cases. Total score of all the five parameters, which was rated as effectiveness score, was calculated by using a standard scale. Final scoring was very effective in six cases, effective in 20 cases, ineffective in four cases.

CONCLUSION

Reconstituted bovine derived collagen membrane used in our study was found to be an effective intraoral wound dressing material for faster uneventful healing of intraorally also.

Soft tissue engineering in craniomaxillofacial surgery

Craniofacial soft tissue reconstruction may be required following trauma, tumor resection, and to repair congenital deformities. Recent advances in the field of tissue engineering have significantly widened the reconstructive armamentarium of the surgeon. The successful identification and combination of tissue engineering, scaffold, progenitor cells, and physiologic signaling molecules has enabled the surgeon to design, recreate the missing tissue in its near natural form. This has resolved the issues like graft rejection, wound dehiscence, or poor vascularity. Successfully reconstructed tissue through soft tissue engineering protocols would help surgeon to restore the form and function of the lost tissue in its originality. This manuscript intends to provide a glimpse of the basic principle of tissue engineering, contemporary, and future direction of this field as applied to craniofacial surgery.