The impact of compositional topography of amniotic membrane scaffold on tissue morphogenesis of salivary gland

Novel Functional Dressing Materials for Intraoral Wound Care

Intraoral wounds represent a particularly challenging category of mucosal and hard tissue injuries, characterized by the unique structures, complex environment, and distinctive healing processes within the oral cavity. They have a common occurrence yet frequently inflict significant inconvenience and pain on patients, causing a serious decline in the quality of life. A variety of novel functional dressings specifically designed for the moist and dynamic oral environment have been developed and realized accelerated and improved wound healing. Thoroughly analyzing and summarizing these materials is of paramount importance in enhancing the understanding and proficiently managing intraoral wounds. In this review, the particular processes and unique characteristics of intraoral wound healing are firstly described. Up-to-date knowledge of various forms, properties, and applications of existing products are then intensively discussed, which are categorized into animal products, plant extracts, natural polymers, and synthetic products. To conclude, this review presents a comprehensive framework of currently available functional intraoral wound dressings, with an aim to provoke inspiration of future studies to design more convenient and versatile materials.

Salispheres from Different Major Salivary Glands for Glandular Regeneration

Dysfunctional salivary glands (SGs) are a clinical challenge due to the lack of effective treatments. Cell therapy with stem/progenitor cells may improve this situation by providing promising therapeutic solutions. Therefore, exploring abundant cellular sources is important. Three major pairs of SGs are located in different anatomic regions: the parotid glands, the submandibular glands, and the sublingual glands. Although SG stem/progenitor cells can be isolated and cultivated from all major SGs as salispheres, the differences among SG origins remain unclear. In this study, salispheres were successfully isolated from all major SGs. The salispheres demonstrated unique cellular features that originated from their native tissues. The characteristic expression profiles and cellular features of SG stem cells were demonstrated in all salispheres. When they were transplanted into irradiated animals, the salispheres were all capable of improving the saliva secretion that was disrupted by irradiation. Typical histologic structures could be observed in most parts of the treated glands, and the fibrotic environments of irradiated submandibular glands were remodeled by all salispheres regardless of origins. This study characterized the cellular features and in vivo effects of salispheres that were derived from different anatomic origins. The results suggest the possibility of functional redundancy among distinct pairs of major SGs, which is useful for the design of cell therapy to treat dysfunctional glandular organs.

Maintenance of the spheroid organization and properties of glandular progenitor cells by fabricated chitosan based biomaterials

Dysfunctional salivary gland (SG) is an unsolved clinical challenge, which is presented as xerostomia. Cell therapy is a promising treatment for restoring SG function. Salispheres are spheroid cellular organizations derived from SG stem cells. Benefitting from these cellular organizations, SG stem cells can be expanded to regenerate SG. During in vitro culture, the spontaneous reorganization of salispheres may change the features of residing SG stem cells. Therefore, it is imperative to explore ways to maintain the spheroid structure of salispheres during cell expansion in vitro. Herein, we explored biomaterial approaches using chitosan. Chitosan based biomaterials were fabricated in different forms to offer distinct interactive surfaces for cultured salispheres. The number and size of the salispheres increase in the chitosan-containing systems without increasing the incidence of spheroid cavitation. The effect of chitosan increases with high chitosan concentrations, which is optimum when chitosan is fabricated in a soluble form. The chitosan effect contributes to the regulation of the intercellular interactions and polarization within the spheroid structures. By retarding the process of salisphere cavitation, chitosan preserves the features of salivary gland progenitor cells in the cultured salispheres. The results suggest that the chitosan-containing system could effectively maintain the primitive structures and properties of salispheres during in vitro expansion, which demonstrates the potential application of salispheres for cell therapy of dysfunctional SG.

Human Amniotic Membrane: A Versatile Scaffold for Tissue Engineering

The human amniotic membrane (hAM) is a collagen-based extracellular matrix derived from the human placenta. It is a readily available, inexpensive, and naturally biocompatible material. Over the past decade, the development of tissue engineering and regenerative medicine, along with new decellularization protocols, has recast this simple biomaterial as a tunable matrix for cellularized tissue engineered constructs. Thanks to its biocompatibility, decellularized hAM is now commonly used in a broad range of medical fields. New preparation techniques and composite scaffold strategies have also emerged as ways to tune the properties of this scaffold. The current state of understanding about the hAM as a biomaterial is summarized in this review. We examine the processing techniques available for the hAM, addressing their effect on the mechanical properties, biodegradation, and cellular response of processed scaffolds. The latest in vitro applications, in vivo studies, clinical trials, and commercially available products based on the hAM are reported, organized by medical field. We also look at the possible alterations to the hAM to tune its properties, either through composite materials incorporating decellularized hAM, chemical cross-linking, or innovative layering and tissue preparation strategies. Overall, this review compiles the current literature about the myriad capabilities of the human amniotic membrane, providing a much-needed update on this biomaterial.

Facilitating In Vivo Articular Cartilage Repair by Tissue-Engineered Cartilage Grafts Produced From Auricular Chondrocytes

BACKGROUND

Insufficient cell numbers still present a challenge for articular cartilage repair. Converting heterotopic auricular chondrocytes by extracellular matrix may be the solution.

HYPOTHESIS

Specific extracellular matrix may convert the phenotype of auricular chondrocytes toward articular cartilage for repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

For in vitro study, rabbit auricular chondrocytes were cultured in monolayer for several passages until reaching status of dedifferentiation. Later, they were transferred to chondrogenic type II collagen (Col II)-coated plates for further cell conversion. Articular chondrogenic profiles, such as glycosaminoglycan deposition, articular chondrogenic gene, and protein expression, were evaluated after 14-day cultivation. Furthermore, 3-dimensional constructs were fabricated using Col II hydrogel-associated auricular chondrocytes, and their histological and biomechanical properties were analyzed. For in vivo study, focal osteochondral defects were created in the rabbit knee joints, and auricular Col II constructs were implanted for repair.

RESULTS

The auricular chondrocytes converted by a 2-step protocol expressed specific profiles of chondrogenic molecules associated with articular chondrocytes. The histological and biomechanical features of converted auricular chondrocytes became similar to those of articular chondrocytes when cultivated with Col II 3-dimensional scaffolds. In an in vivo animal model of osteochondral defects, the treated group (auricular Col II) showed better cartilage repair than did the control groups (sham, auricular cells, and Col II). Histological analyses revealed that cartilage repair was achieved in the treated groups with abundant type II collagen and glycosaminoglycans syntheses rather than elastin expression.

CONCLUSION

The study confirmed the feasibility of applying heterotopic chondrocytes for cartilage repair via extracellular matrix-induced cell conversion.

CLINICAL RELEVANCE

This study proposes a feasible methodology to convert heterotopic auricular chondrocytes for articular cartilage repair, which may serve as potential alternative sources for cartilage repair.

Supportive properties of basement membrane layer of human amniotic membrane enable development of tissue engineering applications

Human amniotic membrane (HAM) has been widely used as a natural scaffold in tissue engineering due to many of its unique biological properties such as providing growth factors, cytokines and tissue inhibitors of metalloproteinases. This study aimed at finding the most suitable and supportive layer of HAM as a delivery system for autologous or allogeneic cell transplantation. Three different layers of HAM were examined including basement membrane, epithelial and stromal layers. In order to prepare the basement membrane, de-epithelialization was performed using 0.5 M NaOH and its efficiency was investigated by histological stainings, DNA quantification, biomechanical testing and electron microscopy. Adipose-derived stromal cells (ASCs) and a human immortalized keratinocyte cell line (HaCaT) were seeded on the three different layers of HAM and cultured for 3 weeks. The potential of the three different layers of HAM to support the attachment and viability of cells were then monitored by histology, electron microscopy and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Moreover, mechanical strengths of the basement membrane were assessed before and after cell culture. The results indicated that the integrity of extra cellular matrix (ECM) components was preserved after de-epithelialization and resulted in producing an intact basement amniotic membrane (BAM). Moreover, all three layers of HAM could support the attachment and proliferation of cells with no visible cytotoxic effects. However, the growth and viability of both cell types on the BAM were significantly higher than the other two layers. We conclude that growth stimulating effectors of BAM and its increased mechanical strength after culturing of ASCs, besides lack of immunogenicity make it an ideal model for delivering allogeneic cells and tissue engineering applications.

The data of establishing a three-dimensional culture system for in vitro recapitulation and mechanism exploration of tumor satellite formation during cancer cell transition

Tumor satellite formation is an indicator of cancer invasiveness and correlates with recurrence, metastasis, and poorer prognosis. By analyzing pathological specimens, tumor satellites formed at the tumor-host interface reflect the phenomena of epithelial-mesenchymal transition. It is impossible to reveal the dynamic processes and the decisive factors of tumor satellite formation using clinicopathological approaches alone. Therefore, establishment of an in vitro system to monitor the phenomena is important to explicitly elucidate underlying mechanisms. In this study, we explored the feasibility of creating an in vitro three-dimensional collagen culture system to recapitulate the process of tumor satellite formation. This data presented here are referred to the research article (Chen et al., 2017) [1]. Using this model, the dynamic process of tumor satellite formation could be recapitulated in different types of human cancer cells. Induced by calcium deprivation, the treated cells increased the incidence and migratory distance of tumor satellites. E-cadherin internalization and invadopodia formation were enhanced by calcium deprivation and were associated with cellular dynamic change during tumor satellite formation. The data confirmed the utility of this culture system to recapitulate dynamic cellular alteration and to explore the potential mechanisms of tumor satellite formation.

Data supporting regulating temporospatial dynamics of morphogen for structure formation of the lacrimal gland by chitosan biomaterials

The lacrimal gland is responsible for tear synthesis and secretion, and is derived from the epithelia of ocular surface and generated by branching morphogenesis. The dataset presented in this article is to support the research results of the effect of chitosan biomaterials on facilitating the structure formation of the lacrimal gland by regulating temporospatial dynamics of morphogen. The embryonic lacrimal gland explants were used as the standard experimental model for investigating lacrimal gland branching morphogenesis. Chitosan biomaterials promoted lacrimal gland branching with a dose-dependent effect. It helped in vivo binding of hepatocyte growth factor (HGF) related molecules in the epithelial-mesenchymal boundary of emerging epithelial branches. When mitogen-activated protein kinase (MAPK) or protein kinase B (Akt/PKB) inhibitors applied, the chitosan effects reduced. Nonetheless, the ratios of MAPK and Akt/PKB phosphorylation were still greater in the chitosan group than the control. The data demonstrated here confirm the essential role of HGF-signaling in chitosan-promoted structure formation of the lacrimal gland.

Regulating temporospatial dynamics of morphogen for structure formation of the lacrimal gland by chitosan biomaterials

The lacrimal gland is an important organ responsible for regulating tear synthesis and secretion. The major work of lacrimal gland (LG) is to lubricate the ocular surface and maintain the health of eyes. Functional deterioration of the lacrimal gland happens because of aging, diseases, or therapeutic complications, but without effective treatments till now. The LG originates from the epithelium of ocular surface and develops by branching morphogenesis. To regenerate functional LGs, it is required to explore the way of recapitulating and facilitating the organ to establish the intricate and ramified structure. In this study, we proposed an approach using chitosan biomaterials to create a biomimetic environment beneficial to the branching structure formation of developing LG. The morphogenetic effect of chitosan was specific and optimized to promote LG branching. With chitosan, increase in temporal expression and local concentration of endogenous HGF-related molecules creates an environment around the emerging tip of LG epithelia. By efficiently enhancing downstream signaling of HGF pathways, the cellular activities and behaviors were activated to contribute to LG branching morphogenesis. The morphogenetic effect of chitosan was abolished by either ligand or receptor deprivation, or inhibition of downstream signaling transduction. Our results elucidated the underlying mechanism accounting for chitosan morphogenetic effects on LG, and also proposed promising approaches with chitosan to assist tissue structure formation of the LG.

Transplantation of human adipose stem cell-derived hepatocyte-like cells with restricted localization to liver using acellular amniotic membrane

Introduction

Adult stem cell-derived hepatocytes transplantation holds considerable promise for future clinical individualized therapy of liver failure or dysfunction. However, the low engraftment of the available hepatocytes in the liver disease microenvironment has been a major obstacle.

Methods

Acellular human amniotic membrane was developed as a three-dimensional scaffold and combined with hepatocyte-like cells derived from human adipose stem cells to engineer a hepatic tissue graft that would allow hepatocyte engraftment in the liver effectively.

Results

The hepatic tissue grafts maintained hepatocyte-specific gene expression and functionality in vitro. When transplanted into the surgical incision in livers for engraftment, the engineered hepatic grafts significantly decreased the degree of liver injury caused by a carbon tetrachloride treatment and generated cords that were similar to the ductal plates in the liver between the acellular human amniotic membrane and the liver of receipts at day 3 post-transplantation. The hepatic tissue grafts maintained the expression of human hepatocyte-specific markers albumin, hepatocyte nuclear factor 4α, and cytochrome P450 2B6 in the liver of receipts, and acquired human-specific drug metabolism ability at eight weeks post-transplantation.

Conclusions

The acellular human amniotic membrane has the ability to maintain the functional phenotype of the hepatocyte-like cells derived from human adipose stem cells. Functional acellular human amniotic membrane-hepatocytes grafts integrated with the liver decreases the acute liver injury of mice. These engineered tissue constructs may support stem cell-based individualized therapy for liver disease and for bioartificial liver establishment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0208-9) contains supplementary material, which is available to authorized users.

Data supporting chitosan facilitates structure formation of the salivary gland by regulating the basement membrane components

To investigate the role of basement membrane (BM) in chitosan-mediated morphogenesis of the salivary glands, the embryonic submandibular gland (SMG) experimental model was used. Chitosan promotes branching at distinct stages in SMG morphogenesis. When enzymes such as type IV collagenase, dispase, and cathepsin B were used to digest the BM components, the morphogenetic effect mediated by chitosan disappeared. Immunofluorescence revealed that the corresponding receptors for BM components, including CD49c, CD49f, CD29, and dystroglycan, were locally enriched at the epithelial-mesenchymal junction around BM areas. The functional roles of laminin α1 and α5 in SMG branching were explored via siRNA knockdown, and suppression was confirmed at both the RNA and protein levels (Yang and Hsiao, Biomaterials, http://dx.doi.org/10.1016/j.biomaterials.2015.06.028, 2015). This data article demonstrates the experimental approaches to investigate the role of basement membrane in the structure formation of the salivary gland engineered by biomaterials.

Chitosan facilitates structure formation of the salivary gland by regulating the basement membrane components

Tissue structure is important for inherent physiological function and should be recapitulated during tissue engineering for regenerative purposes. The salivary gland is a branched organ that is responsible for saliva secretion and regulation. The salivary glands develop from epithelial-mesenchymal interactions, and depend on the support of the basement membrane (BM). Chitosan-based biomaterials have been demonstrated to be competent in facilitating the formation of salivary gland tissue structure. However, the underlying mechanisms have remained elusive. In the developing submandibular gland (SMG), the chitosan effect was found to diminish when collagen and laminin were removed from cultured SMG explants. Chitosan increased the expression of BM components including collagen, laminin, and heparan sulfate proteoglycan, and also facilitated BM components and the corresponding receptors to be expressed in tissue-specific patterns beneficial for SMG branching. The chitosan effect decreased when either laminin components or receptors were inhibited, as well when the downstream signaling was blocked. Our results revealed that chitosan promotes salivary glands branching through the BM. By regulating BM components and receptors, chitosan efficiently stimulated downstream signaling to facilitate salivary gland branching. The present study revealed the underlying mechanism of the chitosan effect in engineering SMG structure formation.

Detection of cell carcinogenic transformation by a quadruplex DNA binding fluorescent probe

Cancer can be easily treated when found early. A probe capable of detecting cell transformation may increase the success rate of early diagnosis of cancer. In this report we have tested the ability of a fluorescent, quadruplex DNA binding probe, 3,6-bis(1-methyl-4- vinylpyridinium) carbazole diiodide (BMVC), to detect cell transformation in vitro. BMVC was applied to living cells in several different models of cell transformation, and the fluorescence signals of BMVC were measured. The degrees of cell transformation in these models were characterized by alterations in cellular morphological phenotype and subcellular organization. When BMVC probes were applied, the number of BMVC-positive cells increased in accordance with the degree of transformation. BMVC was capable of significantly detecting formation of foci, increased cellular motility, cell proliferation, cell apoptosis, anchorage-independent growth, and increased invasiveness of transformed cells. These results demonstrate the ability of BMVC probes to detect cell transformation and indicate that BMVC is of promise for use as a probe in early cancer detection.

Amniotic membrane scaffolds enable the development of tissue-engineered urothelium with molecular and ultrastructural properties comparable to that of native urothelium

The amniotic membrane (AM) is a naturally derived biomaterial that possesses biological and mechanical properties of great importance for tissue engineering. The aim of our study was to determine whether the AM enables the formation of a normal urinary bladder epithelium-urothelium--and to reveal any differences in the urothelial cell (UC) growth and differentiation when using different AM scaffolds. Cryopreserved human AM was used as a scaffold in three different ways. Normal porcine UCs were seeded on the AM epithelium (eAM), denuded AM (dAM), and stromal AM (sAM) and were cultured for 3 weeks. UC growth on AM scaffolds was monitored daily. By using electron microscopy, histochemical and immunofluorescence techniques, we here provide evidence that all three AM scaffolds enable the development of the urothelium. The fastest growth and the highest differentiation of UCs were demonstrated on the sAM scaffold, which enables the development of tissue-engineered urothelium with molecular and ultrastructural properties comparable to that of the native urothelium. Most importantly, the highly differentiated urothelia on the sAM scaffolds provide important experimental models for future drug delivery studies and developing tissue engineering strategies considering that subtle differences are identified before translation to the clinical settings.

Controlling branching structure formation of the salivary gland by the degree of chitosan deacetylation

The salivary gland is characterized by ramified epithelial branches, a specific tissue structure responsible for saliva production and regulation. To regenerate the salivary gland function, it is important to establish the tissue structure. Chitosan is a deacetylated derivative of chitin with wide biomedical applications. Because of its deacetylated nature, chitosan has different properties when prepared with different degrees of deacetylation (DDA). However, the impact of chitosan DDA on the effect of regulating tissue structure formation remains unexplored. In this study, the embryonic murine submandibular gland (SMG) was used as a model to investigate the role of chitosan DDA in regulating tissue structure formation of the salivary gland. When chitin substrates with different DDA were used, the branching numbers of cultured SMG explants changed. Similar effects were observed in the culture with chitosan prepared using different degrees of acetylation. The mRNA expressions of type I and type III collagen were elevated in SMG explants with enhanced branching morphogenesis, as was the protein level. In addition to the amounts of collagen, type I and type III collagen fibers were spatially present in the epithelial-mesenchymal junction of developing branches in the culture with chitosan of a specific range of DDA. The branch-promoting effect of chitosan DDA was abolished when SMG explants were treated with collagenase, both early in the stage of branch initiation and with the establishment of the branching structure. The branch-promoting effect of chitosan DDA disappeared when antisense oligonucleotides were applied to specifically block type III collagen. This study demonstrates for the first time that DDA of chitosan affects tissue structure formation. The different proportions of side-chain components of chitin derivatives regulate structural formation of cultured SMG, indicating that DDA is an important parameter using chitosan as a biomaterial for tissue structure formation of the salivary glands.

The effect of high vacuum on the mechanical properties and bioactivity of collagen fibril matrices

The extracellular matrix (ECM) environment plays a critical role in organism development and disease. Surface sensitive microscopy techniques for studying the structural and chemical properties of ECMs are often performed in high vacuum (HV) environments. In this report, we examine the affect HV conditions have on the bioactivity and mechanical properties of type I collagen fibrillar matrices. We find that HV exposure has an unappreciable affect on the cell spreading response and mechanical properties of these collagen fibril matrices. Conversely, low vacuum environments cause fibrils to become mechanically rigid as indicated by force microscopy, resulting in greater cell spreading. Time-of-flight secondary ion mass spectrometry results show no noticeable spectral differences between HV-treated and dehydrated matrices. While previous reports have shown that HV can denature proteins in monolayers, these observations indicate that HV-exposure does not mechanically or biochemically alter collagen in its supramolecular configuration. These results may have implication for complex ECM matrices such as decellularized scaffolds.

Amniotic membrane in oral and maxillofacial surgery

PURPOSE

Following its renaissance in ophthalmology during the 1990s, preserved human amniotic membrane (HAM) has become an attractive biomaterial for all surgical disciplines. This article reviews the current and potential use of HAM in oral and maxillofacial surgery, its postulated properties and common preservation techniques.

METHODS

Literature was identified by an electronic search of PubMed in July 2012; this was supplemented from the reference lists of the consulted papers.

RESULTS

HAM has been used in the field of oral and maxillofacial surgery from 1969 onwards because of its immunological preference and its pain-reducing, antimicrobial, mechanical and side-dependent adhesive or anti-adhesive properties. The effects of HAM on dermal and mucosal re-epithelialisation have been highlighted. Typically, HAM is applied after being banked in a glycerol-preserved, DMSO-preserved or freeze-dried and irradiated state. Whereas the use of HAM in flap surgery and in intra-oral and extra-oral lining is reported frequently, novel HAM applications in post-traumatic orbital surgery and temporomandibular joint surgery have been added since 2010. Tissue engineering with HAM is a fast-expanding field with a high variety of future options.

CONCLUSIONS

Preserved HAM is considered to be a safe and sufficient biomaterial in all fields of oral and maxillofacial wound healing. Recently published novel indications for HAM application lack a high level of evidence and need to be studied further.

Chitin-based materials in tissue engineering: applications in soft tissue and epithelial organ

Chitin-based materials and their derivatives are receiving increased attention in tissue engineering because of their unique and appealing biological properties. In this review, we summarize the biomedical potential of chitin-based materials, specifically focusing on chitosan, in tissue engineering approaches for epithelial and soft tissues. Both types of tissues play an important role in supporting anatomical structures and physiological functions. Because of the attractive features of chitin-based materials, many characteristics beneficial to tissue regeneration including the preservation of cellular phenotype, binding and enhancement of bioactive factors, control of gene expression, and synthesis and deposition of tissue-specific extracellular matrix are well-regulated by chitin-based scaffolds. These scaffolds can be used in repairing body surface linings, reconstructing tissue structures, regenerating connective tissue, and supporting nerve and vascular growth and connection. The novel use of these scaffolds in promoting the regeneration of various tissues originating from the epithelium and soft tissue demonstrates that these chitin-based materials have versatile properties and functionality and serve as promising substrates for a great number of future applications.

Characterizing nanoscale topography of the aortic heart valve basement membrane for tissue engineering heart valve scaffold design

A fully effective prosthetic heart valve has not yet been developed. A successful tissue-engineered valve prosthetic must contain a scaffold that fully supports valve endothelial cell function. Recently, topographic features of scaffolds have been shown to influence the behavior of a variety of cell types and should be considered in rational scaffold design and fabrication. The basement membrane of the aortic valve endothelium provides important parameters for tissue engineering scaffold design. This study presents a quantitative characterization of the topographic features of the native aortic valve endothelial basement membrane; topographical features were measured, and quantitative data were generated using scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and light microscopy. Optimal conditions for basement membrane isolation were established. Histological, immunohistochemical, and TEM analyses following decellularization confirmed basement membrane integrity. SEM and AFM photomicrographs of isolated basement membrane were captured and quantitatively analyzed. The basement membrane of the aortic valve has a rich, felt-like, 3-D nanoscale topography, consisting of pores, fibers, and elevations. All features measured were in the sub-100 nm range. No statistical difference was found between the fibrosal and ventricular surfaces of the cusp. These data provide a rational starting point for the design of extracellular scaffolds with nanoscale topographic features that mimic those found in the native aortic heart valve basement membrane.