How Fiber Surface Topography Affects Interactions between Cells and Electrospun Scaffolds: A Systematic Review

Electrospun scaffolds have a 3D fibrous structure that attempts to imitate the extracellular matrix in order to be able to host cells. It has been reported in the literature that controlling fiber surface topography produces varying results regarding cell–scaffold interactions. This review analyzes the relevant literature concerning in vitro studies to provide a better understanding of the effect that controlling fiber surface topography has on cell–scaffold interactions. A systematic approach following PRISMA, GRADE, PICO, and other standard methodological frameworks for systematic reviews was used. Different topographic interventions and their effects on cell–scaffold interactions were analyzed. Results indicate that nanopores and roughness on fiber surfaces seem to improve proliferation and adhesion of cells. The quality of the evidence is different for each studied cell–scaffold interaction, and for each studied morphological attribute. The evidence points to improvements in cell–scaffold interactions on most morphologically complex fiber surfaces. The discussion includes an in-depth evaluation of the indirectness of the evidence, as well as the potentially involved publication bias. Insights and suggestions about dose-dependency relationship, as well as the effect on particular cell and polymer types, are presented. It is concluded that topographical alterations to the fiber surface should be further studied, since results so far are promising.

The Effect of Collagen-I Coatings of 3D Printed PCL Scaffolds for Bone Replacement on Three Different Cell Types

Introduction The use of scaffolds in tissue engineering is becoming increasingly important as solutions need to be found to preserve human tissues such as bone or cartilage. Various factors, including cells, biomaterials, cell and tissue culture conditions, play a crucial role in tissue engineering. The in vivo environment of the cells exerts complex stimuli on the cells, thereby directly influencing cell behavior, including proliferation and differentiation. Therefore, to create suitable replacement or regeneration procedures for human tissues, the conditions of the cells’ natural environment should be well mimicked. Therefore, current research is trying to develop 3-dimensional scaffolds (scaffolds) that can elicit appropriate cellular responses and thus help the body regenerate or replace tissues. In this work, scaffolds were printed from the biomaterial polycaprolactone (PCL) on a 3D bioplotter. Biocompatibility testing was used to determine whether the printed scaffolds were suitable for use in tissue engineering. Material and Methods An Envisiontec 3D bioplotter was used to fabricate the scaffolds. For better cell-scaffold interaction, the printed polycaprolactone scaffolds were coated with type-I collagen. Three different cell types were then cultured on the scaffolds and various tests were used to investigate the biocompatibility of the scaffolds. Results Reproducible scaffolds could be printed from polycaprolactone. In addition, a coating process with collagen was developed, which significantly improved the cell-scaffold interaction. Biocompatibility tests showed that the PCL-collagen scaffolds are suitable for use with cells. The cells adhered to the surface of the scaffolds and as a result extensive cell growth was observed on the scaffolds. The inner part of the scaffolds, however, remained largely uninhabited. In the cytotoxicity studies, it was found that toxicity below 20% was present in some experimental runs. The determination of the compressive strength by means of the universal testing machine Z005 by ZWICK according to DIN EN ISO 604 of the scaffolds resulted in a value of 68.49 ± 0.47 MPa.

Scaffolds with Magnetic Nanoparticles for Tissue Stimulation

Magnetic nanoparticles (MNPs) have been used in several medical applications, including targeted hyperthermia, resonance tomography, diagnostic sensors, and localized drug delivery. Further applications of magnetic field manipulation through MNPs in tissue engineering have been described. The current study aims to develop tissue-engineered polymeric scaffolds with incorporated MNPs for applications that require stimulation of the tissues such as nerves, muscles, or heart. Electrospun scaffolds were obtained using 14%w/v polycaprolactone (PCL) in 2,2,2-Trifluoroethanol (TFE) at concentrations of 5% & 7.5%w/v of dispersed MNPs (iron oxide, Fe3O4, or cobalt iron oxide, CoFe2O4). Scaffolds were analyzed using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy, uniaxial tensile testing, and cell seeding for biocompatibility. Human bone marrow mesenchymal stem cells (bmMSCs) were seeded on the scaffolds. Biocompatibility was assessed by metabolic activity with Resazurin reduction assay on day 1, 3, 7, 10. Cell-cell and cell-scaffold interactions were analyzed by SEM. Electrospun scaffolds containing MNPs showed a decrease in fiber diameter as compared to scaffolds of pure PCL. The maximum force increases with the inclusion of MNPs, with higher values revealed for iron oxide. The metabolic activity decreased with MNPs, especially for cobalt iron oxide at a higher concentration. On the other hand, the cells developed good cell-scaffold and cell-cell interactions, making the proposed scaffolds good prospects for potential use in tissue stimulation.

Electrospinning and Electrospraying with Cells for Applications in Biomanufacturing

Biomanufacturing of cell-laden scaffolds with biomimetic cell-scaffold organizations resembling the structures and anatomy of human body tissues and organs holds great promise in tissue engineering and regenerative medicine. In human body tissues and organs, specific types of cells are supported by nanofibrous extracellular matrix (ECM) in well-defined three-dimensional (3D) manners. Electrospinning is a facile and effective technique for producing nanofibrous scaffolds, which exhibit high similarities in the structure compared to ECM that offers structural and mechanical supports to cells in the human body. The incorporation within the electrospun nanofibrous scaffolds has therefore been considered as a promising approach for biomanufacturing of cell-laden scaffolds with tissue-mimicking structures. However, limited by low controllability of conventional cell seeding strategies and small sizes of interconnected pores of normal electrospun scaffolds, it is highly difficult to incorporate living cells within electrospun scaffolds on demand and results in cell-laden scaffolds with desirable 3D cell-scaffold organization. With recent advances in electrospinning and electrospraying with cells, it is visible to directly incorporate living cells within scaffolds via cell microencapsulation approaches and therefore offer promising alternatives for biomanufacturing of cell-laden scaffolds with tissue-mimicking structures. In this review, we will summarize the applications and challenges of cell seeding strategies and cell microencapsulation technologies for incorporating cells within electrospun scaffolds. Some techniques with high potentials to be integrated with electrospinning for forming the cell-laden scaffolds in continuous and noncontact manners, including aerodynamic-assisted cell microencapsulation, hydrodynamic-assisted cell microencapsulation and electrohydrodynamic-assisted cell microencapsulation (i.e., cell electrospinning and cell electrospraying), are highlighted. In particular, the cell microencapsulation and the subsequent formation of cell-laden scaffolds directly by electrospinning and electrospraying with living cells are overviewed in a detailed manner. Finally, the perspective and challenges of electrospinning and electrospraying with cells for biomanufacturing of cell-laden scaffolds with tissue-mimicking structures are discussed.

Ethanol treatment of nanoPGA/PCL composite scaffolds enhances human chondrocyte development in the cellular microenvironment of tissue-engineered auricle constructs

A major obstacle for tissue engineering ear-shaped cartilage is poorly developed tissue comprising cell-scaffold constructs. To address this issue, bioresorbable scaffolds of poly-ε-caprolactone (PCL) and polyglycolic acid nanofibers (nanoPGA) were evaluated using an ethanol treatment step before auricular chondrocyte scaffold seeding, an approach considered to enhance scaffold hydrophilicity and cartilage regeneration. Auricular chondrocytes were isolated from canine ears and human surgical samples discarded during otoplasty, including microtia reconstruction. Canine chondrocytes were seeded onto PCL and nanoPGA sheets either with or without ethanol treatment to examine cellular adhesion in vitro. Human chondrocytes were seeded onto three-dimensional bioresorbable composite scaffolds (PCL with surface coverage of nanoPGA) either with or without ethanol treatment and then implanted into athymic mice for 10 and 20 weeks. On construct retrieval, scanning electron microscopy showed canine auricular chondrocytes seeded onto ethanol-treated scaffolds in vitro developed extended cell processes contacting scaffold surfaces, a result suggesting cell-scaffold adhesion and a favorable microenvironment compared to the same cells with limited processes over untreated scaffolds. Adhesion of canine chondrocytes was statistically significantly greater (p ≤ 0.05) for ethanol-treated compared to untreated scaffold sheets. After implantation for 10 weeks, constructs of human auricular chondrocytes seeded onto ethanol-treated scaffolds were covered with glossy cartilage while constructs consisting of the same cells seeded onto untreated scaffolds revealed sparse connective tissue and cartilage regeneration. Following 10 weeks of implantation, RT-qPCR analyses of chondrocytes grown on ethanol-treated scaffolds showed greater expression levels for several cartilage-related genes compared to cells developed on untreated scaffolds with statistically significantly increased SRY-box transcription factor 5 (SOX5) and decreased interleukin-1α (inflammation-related) expression levels (p ≤ 0.05). Ethanol treatment of scaffolds led to increased cartilage production for 20- compared to 10-week constructs. While hydrophilicity of scaffolds was not assessed directly in the present findings, a possible factor supporting the summary data is that hydrophilicity may be enhanced for ethanol-treated nanoPGA/PCL scaffolds, an effect leading to improvement of chondrocyte adhesion, the cellular microenvironment and cartilage regeneration in tissue-engineered auricle constructs.

Investigation of the Regenerative Potential of Human Bone Marrow Stem Cell-Seeded Polycaprolactone Bone Scaffolds, Fabricated Using Pneumatic Microextrusion Process

Pneumatic MicroExtrusion (PME) is a direct-write additive manufacturing process, which has emerged as a robust, high-resolution method for the fabrication of a broad spectrum of biological tissues and organs. However, the PME process is intrinsically complex, governed by bio-physio-chemical phenomena as well as material-process interactions. Hence, investigation of the influence of consequential factors on bone scaffold fabrication as well as investigation of cell-scaffold interactions would be an inevitable need. The objective of the work is to investigate the biocompatibility as well as the histological properties of PME-fabricated porous bone scaffolds, composed of polycaprolactone (PCL). To achieve this objective, a media extraction of the scaffold material was tested for cytostatic or cytotoxic activity with the aim to: (i) assess the fabricated scaffolds’ feasibility of use in regenerative medicine, and (ii) determine their structural integrity in a modelled in-vivo environment. In addition, the scaffolds were inoculated with an established osteosarcoma cell line (SAOS-2) and cultured for seven days to investigate the scaffold architecture and cell integration potential. A histological examination was performed on the seeded scaffolds for further in-depth analysis of cell-scaffold interaction. Overall, the results of this study pave the way for future investigation of stem cell incorporation into PME-fabricated PCL scaffolds toward the treatment of osseous fractures and defects.

Female Bioengineering: Primordial Germ Cell Differentiation of Mesenchymal Stem Cells onto Placental Scaffolds

Introduction: Female infertility is a condition that is currently treated through the maximization of existing reserves; a necessity due to the fact that a true reversal of the processes leading to infertility is not yet technologically possible. This experiment examined the ability of mesenchymal stem cells to differentiate into primordial germ cells (PGC) when cultured onto the placental scaffold. Methods: To produce the scaffolds, the cotelydons were collected and decellularized by umbilical vessel SDS perfusion. Adipose derived cells were isolated based on rapid adherence to the plastic. Results: The isolated cells displayed the markers CD90 and 105, while lacked CD34 and CD45. When seeded onto the scaffold, the cells successfully differentiated into PGC like cells, displaying typical PGCs markers, including STELLA, OCT4, DAZL and VASA. Discussion: These materials were chosen for their low cost and wide availability. The data in this study show the promising potential of cell-scaffold complex to support the development of female tissue engineering-based regenerative medicine therapies.

A Preliminary Study of Constructing Tissue Engineered Oral Mucosa

Background: Adipose derived stem cells (ADSCs) have a great potential for tissue-engineering purposes, and they may be introduced in oral mucosa tissue engineering for urethroplasty. This study was aim to develop a tissue-engineered oral mucosa through seeding oral keratinocytes (OKs) and adipose derived stem cells (ADSCs) on small intestine submucosa (SIS). Methods: SIS was obtained from porcine small intestine, and OKs and ADSCs were obtained from canine sources and were cultured and expanded in vitro. The two cell lines were seeded on the two surfaces of the SIS, and the cell-scaffold compound graft was cultured in an air fluid level for 1 week.Results: The SIS exhibited a porous membrane, and no cells were found through HE staining. The model cultured with OK-SIS only formed a thin and loose epithelium. Whereas the model cultured with OK-SIS-ADSC was much thicker and denser. Conclusion: The co-cultured of ADSC and OK grew well on the SIS in which the OKs formed a multilayer of epithelium. So it is feasible to construct a tissue-engineered oral mucosa graft with ADSCs, OKs and SIS. The ADSCs contribute to a thicker epithelium formation.