Cellular Interactions and Biomechanical Properties of a Unique Vascular-Derived Scaffold for Periodontal Tissue Regeneration

Advances Focusing on the Application of Decellularized Extracellular Matrix in Periodontal Regeneration

The decellularized extracellular matrix (dECM) is capable of promoting stem cell proliferation, migration, adhesion, and differentiation. It is a promising biomaterial for application and clinical translation in the field of periodontal tissue engineering as it most effectively preserves the complex array of ECM components as they are in native tissue, providing ideal cues for regeneration and repair of damaged periodontal tissue. dECMs of different origins have different advantages and characteristics in promoting the regeneration of periodontal tissue. dECM can be used directly or dissolved in liquid for better flowability. Multiple ways were developed to improve the mechanical strength of dECM, such as functionalized scaffolds with cells that harvest scaffold-supported dECM through decellularization or crosslinked soluble dECM that can form injectable hydrogels for periodontal tissue repair. dECM has found recent success in many periodontal regeneration and repair therapies. This review focuses on the repairing effect of dECM in periodontal tissue engineering, with variations in cell/tissue sources, and specifically discusses the future trend of periodontal regeneration and the future role of soluble dECM in entire periodontal tissue regeneration.

Effect of book-shaped acellular tendon scaffold with bone marrow mesenchymal stem cells sheets on bone-tendon interface healing

Background

Tissue engineering has exhibited great effect on treatment for bone-tendon interface (BTI) injury. The aim of this study was to evaluate the effect of a book-shaped acellular tendon scaffold (ATS) with bone marrow mesenchymal stem cells sheets (MSCS) for BTI injury repair.

Methods

ATS was designed based on the shape of "book", decellularization effect was evaluated by Hematoxylin and eosin (H&E), 4', 6-diamidino-2-phenylindole (DAPI) and scanning electron microscopy (SEM), then bone marrow mesenchymal stem cells (MSCs) were cultured on ATS to assess the differentiation inductivity of ATS. A rabbit right partial patellotomy model was established, and MSCS seeded on ATS were implanted into the lesion site. The patella-patellar tendon (PPT) at 2, 4, 8 or 16 weeks post-operation were obtained for histological, biomechanical and immunofluorescence analysis.

Results

H&E, DAPI and SEM results confirmed the efficiency of decellularization of ATS, and their in vitro tenogenic and chondrogenic ability were successfully identified. In vivo results showed increased macrophage polarization toward the M2 phenotype, IL-10 expression, regenerated bone and fibrocartilage at the patella-patellar tendon interface of animals received MSCS modified ATS implantation. In addition, the level of tensile strength was also the highest in MSCS modified ATS implantation group.

Conclusion

This study suggests that ATS combined with MSCS performed therapeutic effects on promoting the regeneration of cartilage layer and enhancing the healing quality of patella-patellar tendon interface.

The translational potential of this article

This study showed the good biocompatibility of the ATS, as well as the great efficacy of ATS with MSCS on tendon to bone healing. The results meant that the novel book-shaped ATS with MSCS may have a great potential for clinical application.

Umbilical cord tissue cryopreservation: a short review

In this review we present current evidence on the possibility of umbilical cord tissue cryopreservation for subsequent clinical use. Protocols for obtaining umbilical cord-derived vessels, Wharton’s jelly-based grafts, multipotent stromal cells, and other biomedical products from cryopreserved umbilical cords are highlighted, and their prospective clinical applications are discussed. Examination of recent literature indicates we should expect high demand for cryopreservation of umbilical cord tissues in the near future.

Laser micro-ablation of fibrocartilage tissue: Effects of tissue processing on porosity modification and mechanics

The temporomandibular joint disk (TMJd) is an extremely dense and avascular fibrocartilaginous extracellular matrix (ECM) resulting in a limited regenerative capacity. The use of decellularized TMJd as a biocompatible scaffold to guide tissue regeneration is restricted by innate subcellular porosity of the ECM that hinders cellular infiltration and regenerative events. Incorporation of an artificial microporosity through laser micro-ablation (LMA) can alleviate these cell and diffusion based limitations. In this study, LMA was performed either before or after decellularization to assess to effect of surfactant treatment on porosity modification as well as the resultant mechanical and physical scaffold properties. Under convective flow or agitation schemes, pristine and laser ablated disks were decellularized using either low (0.1% w/v) or high (1% w/v) concentrations of sodium dodecyl sulfate (SDS). Results show that lower concentrations of SDS minimized collagen degradation and tissue swelling while retaining its capacity to solubilize cellular content. Regardless of processing scheme, laser ablated channels incorporated after SDS treatment were relatively smaller and more uniform than those incorporated before SDS treatment, indicating an altered laser interaction with surfactant treated tissues. Smaller channels correlated with less disruption of native biomechanical properties indicating surfactant pre-treatment is an important consideration when using LMA to produce artificial porosity in ex vivo derived tissues. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1858-1868, 2018.

Human Perinatal-Derived Biomaterials

Human perinatal tissues have been used for over a century as allogeneic biomaterials. Due to their advantageous properties including angiogenecity, anti-inflammation, anti-microbial, and immune privilege, these tissues are being utilized for novel applications across wide-ranging medical disciplines. Given continued clinical success, increased adoption of perinatal tissues as a disruptive technology platform has allowed for significant penetration into the multi-billion dollar biologics market. Here, we review current progress and future applications of perinatal biomaterials, as well as associated regulatory issues.

Preimplantation processing of ex vivo-derived vascular biomaterials: effects on peripheral cell adhesion

The use of ex vivo-derived scaffolds as vascular conduits has shown to be a clinically valid approach to repair or bypass occluded vessels. Implantation of allogeneic tissue grafts requires careful processing to lower immunogenicity and prevent bacterial infection. However, the mechanical/chemical treatments used to prepare biological scaffolds can result in significant alterations to the native structure and surface chemistry, which can affect in vivo performance. Of particular importance for vascular grafts are binding interactions between the implanted biomaterial and host cells from the circulation and adjacent vasculature. Here we present a comparison of four strategies used to decellularize allogeneic human umbilical vein (HUV) scaffolds: ethanol/acetone, sodium chloride, sodium dodecyl sulfate (SDS), or Triton X-100. Scanning electron microscopy revealed that all four techniques achieved removal of native cells from both the lumenal and ablumenal surfaces of HUV grafts. Platelets and promyelocytic HL-60 cells showed preferential binding on the more loosely structured ablumenal surface, although low surface coverage was observed overall by peripheral blood cells. Vascular endothelial cell adhesion was highest on HUV decellularized using ethanol/acetone, and significantly higher than on SDS-processed grafts (p = 0.016). Primary cells showed high viability on the lumenal surface regardless of decellularization technique (over 95% in all cases). These results demonstrate the critical effects of various chemical processing strategies on the adhesive properties of ex vivo-derived vascular grafts. Careful application-specific consideration is warranted when selecting a processing strategy that minimizes innate responses (e.g. thrombosis, inflammation) that are often deleterious to graft survival.

Biomechanical behavior of oral soft tissues

BACKGROUND

Little attention has been given to understanding the variation in biomechanical behavior of oral soft tissues, and this represents an obstacle for the development of biomaterials that perform with appropriate biomechanical characteristics. With this as our motivation, a uniaxial mechanical analysis was performed on lingual and buccal aspects of the attached gingiva, alveolar mucosa, and buccal mucosa to gain insight into human tissue performance and site-specific mechanical variation.

METHODS

A discrete quantitative mechanical evaluation of each soft tissue region using tensile, dynamic compression, and stress relaxation analysis was conducted to correlate tissue structure with function as assessed histologically.

RESULTS

Results confirm the keratinized gingiva to have increased tensile strength (3.94 ± 1.19 MPa) and stiffness (Young modulus of 19.75 ± 6.20 MPa) relative to non-keratinized mucosal regions, where densely arranged elastin fibers contribute to a tissue with increased viscoelastic properties. Dynamic compression analysis indicated the instantaneous modulus (E(int)), steady modulus (E(s)), and peak stress increased with loading frequency and strain amplitude, with the highest values found in the buccal attached gingiva.

CONCLUSION

These investigations quantify the biomechanical properties of oral soft tissues and show region-to-region variation that details structure-function relationships and provides key parameters to aid development of biomaterials that perform with appropriate biomechanical properties.