Electrospun polymer biomaterials

Electrospun nanofibers for wound healing.

Patients with extensive burns rely on the use of tissue engineered skin due to a lack of sufficient donor tissue, but it is a challenge to identify reliable and economical scaffold materials and donor cell sources for the generation of a functional skin substitute. The current review attempts to evaluate the performance of the wide range of biomaterials available for generating skin substitutes, including both natural biopolymers and synthetic polymers, in terms of tissue response and potential for use in the operating room. Natural biopolymers display an improved cell response, while synthetic polymers provide better control over chemical composition and mechanical properties. It is suggested that not one material meets all the requirements for a skin substitute. Rather, a composite scaffold fabricated from both natural and synthetic biomaterials may allow for the generation of skin substitutes that meet all clinical requirements including a tailored wound size and type, the degree of burn, the patient age, and the available preparation technique. This review aims to be a valuable directory for researchers in the field to find the optimal material or combination of materials based on their specific application.

Biomaterials for Skin Substitutes.

Tissue engineering and regenerative medicine are emerging as future approaches for the treatment of acute and chronic diseases. Numerous clinical conditions exist today and include congenital disorders, trauma, infection, inflammation, and cancer, in which hard and soft tissue damage, organ failure and loss are still not treated effectively. Researchers are constantly developing new biomaterials and tissue-engineered technologies to stimulate tissue regeneration. Various emerging approaches according to organ, tissue, disease and disorder are identified. Irrespective, engineered biomaterials are required to regenerate and ultimately reproduce the original physiological, biological, chemical, and mechanical properties. Biodegradable materials have been used extensively as regenerative therapies. The selection, design, biological and physicochemical properties of these materials are important and must be considered for stimulating tissue growth. In this review, we critique recently developed biodegradable materials for tissue regeneration of some targeted organs e.g., skin, nerves, blood vessels, heart, cornea, trachea, dental/oral structure and bones.

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Recent concepts in biodegradable polymers for tissue engineering paradigms: a critical review

Electrospinning is a simple and versatile technique to fabricate continuous fibers with diameter ranging from micrometers to a few nanometers. To date, the number of polymers that have been electrospun has exceeded 200. In recent years, electrospinning has become one of the most popular scaffold fabrication techniques to prepare nanofiber mesh for tissue engineering applications. Collagen, the most abundant extracellular matrix protein in the human body, has been electrospun to fabricate biomimetic scaffolds that imitate the architecture of native human tissues. As collagen nanofibers are mechanically weak in nature, it is commonly cross-linked or blended with synthetic polymers to improve the mechanical strength without compromising the biological activity. Electrospun collagen nanofiber mesh has high surface area to volume ratio, tunable diameter and porosity, and excellent biological activity to regulate cell function and tissue formation. Due to these advantages, collagen nanofibers have been tested for the regeneration of a myriad of tissues and organs. In this review, we gave an overview of electrospinning, encompassing the history, the instrument settings, the spinning process and the parameters that affect fiber formation, with emphasis given to collagen nanofibers' fabrication and application, especially the use of collagen nanofibers in skin tissue engineering.

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Electrospun Collagen Nanofibers and Their Applications in Skin Tissue Engineering

Electrospinning is a technique for creating continuous nanofibrous networks that can architecturally be similar to the structure of extracellular matrix (ECM). However, the shrinkage of electrospun mats is unfavorable for the triggering of cell adhesion and further growth. In this work, electrospun PLGA nanofiber assemblies are utilized to create a scaffold. Aided by a polypropylene auxiliary supporter, the scaffold is able to maintain long-term integrity without dimensional shrinkage. This scaffold is also able to suspend in cell culture medium; hence, keratinocyte cells seeded on the scaffold are exposed to air as required in skin tissue engineering. Experiments also show that human skin keratinocytes can proliferate on the scaffold and infiltrate into the scaffold.

Suspended, Shrinkage-Free, Electrospun PLGA Nanofibrous Scaffold for Skin Tissue Engineering

Polycaprolactone (PCL) is a polymer material suitable for being prepared into porous scaffolds used in bone tissue engineering, however, insufficient osteogenic ability and mechanical strength limit its application. Zinc (Zn) alloy with proper mechanical strength and osteogenesis is a promising biodegradable metal that have attracted much attention. Herein, we combined the advantages of PCL and Zn by fabricating PCL/Zn composite scaffolds with different Zn powder contents (1 ​wt%, 2 ​wt%, 3 ​wt%) through fused deposition modelling. The ​mechanical property, cytocompatibility and Zn ​ions release ​behavior of PCL/Zn scaffolds were analyzed ​in vitro. The osteogenesis and osteoclastogenesis properties of the scaffolds were evaluated by being implanted into Sprague-Dawley rats calvaria defect. Results showed that the PCL/Zn scaffolds exhibited improved mechanical properties and cytocompatibility compared with the pure PCL scaffolds. At 8 weeks after in vivo implantaion, the addition of Zn powder promoted new bone formation, in a dose-dependent manner. The scaffolds with 2 ​wt% Zn displayed the best osteogenic effect, while the osteogenic effect was slightly reduced in the scaffolds with 3 ​wt% Zn. In the studied Zn contents, the PCL/Zn scaffolds gradually promoted osteoclastogenesis with increasd Zn content. In the 3 ​wt% Zn group, TRAP-positive cells were observed on the newly formed bone edges around the scaffolds. These dose-dependent effects were verified in vitro using MC3T3-E1 and RAW264.7 ​cells. Finally, we revealed that Zn2+ regulated osteogenesis and osteoclastogenesis by activation of the Wnt/β-catenin and NF-κB signalling pathways, respectively. 

https://doi.org/10.1016/j.mtbio.2021.100202

3D-Printed PCL/Zn scaffolds for bone regeneration with a dose-dependent effect on osteogenesis and osteoclastogenesis

The effect of near-infrared light-assisted photothermal therapy combined with polymer materials on promoting bone regeneration: a systematic review

Abstract Background When evaluating the efficacy and safety of various desensitizing products in vitro, their mechanism of action and clinical utility should be considered during test model selection. This study aimed to evaluate the effects of two desensitizers, an in-office use material and an at-home use material, on dentin specimen permeability, and their dentin barrier cytotoxicity with appropriate test models. Methods Two materials, GLUMA desensitizer (GLU) containing glutaraldehyde and remineralizing and desensitizing gel (RD) containing sodium fluoride and fumed silica, were selected. Human dentin specimens were divided into three groups (n = 6): in groups 1 and 2, GLU was applied, and in group 3, RD was applied and immersed in artificial saliva (AS) for 24 h. Dentin specimen permeability before and after each treatment/post-treatment was measured using a hydraulic device under a pressure of 20 cm H 2 O. The perfusion fluid was deionized water, except in group 2 where 2% bovine serum albumin (BSA) was used. The representative specimens before and after treatment from each group were investigated using scanning electron microscopy. To measure cytotoxicity, test materials were applied to the occlusal surfaces of human dentin disks under which three-dimensional cell scaffolds were placed. After 24-h contact within the test device, cell viability was measured via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Results GLU significantly reduced the dentin permeability and occluded the dentinal tubules when 2% BSA was used as perfusion fluid. RD significantly reduced dentin permeability and occluded the tubules, but permeability rebounded after AS immersion. GLU significantly decreased cell viability, but RD was non-cytotoxic. Conclusions In vitro GLU application induced effective dentinal tubule occlusion only following the introduction of simulated dentinal fluid. RD provided effective tubule occlusion, but its full remineralization potential was not realized after a short period of immersion in AS. GLU may harm the pulp, whereas RD is sufficiently biocompatible. 

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Effectiveness and cytotoxicity of two desensitizing agents: a dentin permeability measurement and dentin barrier testing in vitro study

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Feilong Wang

Papers

Suspended, Shrinkage-Free, Electrospun PLGA Nanofibrous Scaffold for Skin Tissue Engineering

3D-Printed PCL/Zn scaffolds for bone regeneration with a dose-dependent effect on osteogenesis and osteoclastogenesis

The effect of near-infrared light-assisted photothermal therapy combined with polymer materials on promoting bone regeneration: a systematic review

Effectiveness and cytotoxicity of two desensitizing agents: a dentin permeability measurement and dentin barrier testing in vitro study

Effectiveness and cytotoxicity of two desensitizing agents: a dentin permeability measurement and dentin barrier testing in vitro study