Near-field electrospinning of a polymer/bioactive glass composite to fabricate 3D biomimetic structures

The Synergetic Effect of 3D Printing and Electrospinning Techniques in the Fabrication of Bone Scaffolds

The primary goal of bone tissue engineering is to restore and rejuvenate bone defects by using a suitable three-dimensional scaffold, appropriate cells, and growth hormones. Various scaffolding methods are used to fabricate three-dimensional scaffolds, which provide the necessary environment for cell activity and bone formation. Multiple materials may be used to create scaffolds with hierarchical structures that are optimal for cell growth and specialization. This study examines a notion for creating an optimal framework for bone regeneration using a combination of the robocasting method and the electrospinning approach. Research indicates that the integration of these two procedures enhances the benefits of each method and provides a rationale for addressing their shortcomings via this combination. The hybrid approach is anticipated to provide a manufactured scaffold that can effectively replace bone defects while possessing the necessary qualities for bone regeneration.

Biomaterials combined with ADSCs for bone tissue engineering: current advances and applications

In recent decades, bone tissue engineering, which is supported by scaffold, seed cells and bioactive molecules (BMs), has provided new hope and direction for treating bone defects. In terms of seed cells, compared to bone marrow mesenchymal stem cells, which were widely utilized in previous years, adipose-derived stem cells (ADSCs) are becoming increasingly favored by researchers due to their abundant sources, easy availability and multi-differentiation potentials. However, there is no systematic theoretical basis for selecting appropriate biomaterials loaded with ADSCs. In this review, the regulatory effects of various biomaterials on the behavior of ADSCs are summarized from four perspectives, including biocompatibility, inflammation regulation, angiogenesis and osteogenesis, to illustrate the potential of combining various materials with ADSCs for the treatment of bone defects. In addition, we conclude the influence of additional application of various BMs on the bone repair effect of ADSCs, in order to provide more evidences and support for the selection or preparation of suitable biomaterials and BMs to work with ADSCs. More importantly, the associated clinical case reports and experiments are generalized to provide additional ideas for the clinical transformation and application of bone tissue engineering loaded with ADSCs.

Bioactive and Biodegradable Polycaprolactone-Based Nanocomposite for Bone Repair Applications

This study investigated the relationship between the structure and mechanical properties of polycaprolactone (PCL) nanocomposites reinforced with baghdadite, a newly introduced bioactive agent. The baghdadite nanoparticles were synthesised using the sol-gel method and incorporated into PCL films using the solvent casting technique. The results showed that adding baghdadite to PCL improved the nanocomposites' tensile strength and elastic modulus, consistent with the results obtained from the prediction models of mechanical properties. The tensile strength increased from 16 to 21 MPa, and the elastic modulus enhanced from 149 to 194 MPa with fillers compared to test specimens without fillers. The thermal properties of the nanocomposites were also improved, with the degradation temperature increasing from 388 °C to 402 °C when 10% baghdadite was added to PCL. Furthermore, it was found that the nanocomposites containing baghdadite showed an apatite-like layer on their surfaces when exposed to simulated body solution (SBF) for 28 days, especially in the film containing 20% nanoparticles (PB20), which exhibited higher apatite density. The addition of baghdadite nanoparticles into pure PCL also improved the viability of MG63 cells, increasing the viability percentage on day five from 103 in PCL to 136 in PB20. Additionally, PB20 showed a favourable degradation rate in PBS solution, increasing mass loss from 2.63 to 4.08 per cent over four weeks. Overall, this study provides valuable insights into the structure-property relationships of biodegradable-bioactive nanocomposites, particularly those reinforced with new bioactive agents.

Functionalized 3D-Printed ST2/Gelatin Methacryloyl/Polcaprolactone Scaffolds for Enhancing Bone Regeneration with Vascularization

Growth factors were often used to improve the bioactivity of biomaterials in order to fabricate biofunctionalized bone grafts for bone defect repair. However, supraphysiological concentrations of growth factors for improving bioactivity could lead to serious side effects, such as ectopic bone formation, radiculitis, swelling of soft tissue in the neck, etc. Therefore, safely and effectively applying growth factors in bone repair biomaterials comes to be an urgent problem that needs to be addressed. In this study, an appropriate concentration (50 ng/mL) of Wnt3a was used to pretreat the 3D-bioprinting gelatin methacryloyl(GelMA)/polycaprolactone(PCL) scaffold loaded with bone marrow stromal cell line ST2 for 24 h. This pretreatment promoted the cell proliferation, osteogenic differentiation, and mineralization of ST2 in the scaffold in vitro, and enhanced angiogenesis and osteogenesis after being implanted in critical-sized mouse calvarial defects. On the contrary, the inhibition of Wnt/β-catenin signaling in ST2 cells reduced the bone repair effect of this scaffold. These results suggested that ST2/GelMA/PCL scaffolds pretreated with an appropriate concentration of Wnt3a in culture medium could effectively enhance the osteogenic and angiogenic activity of bone repair biomaterials both in vitro and in vivo. Moreover, it would avoid the side effects caused by the supraphysiological concentrations of growth factors. This functionalized scaffold with osteogenic and angiogenic activity might be used as an outstanding bone substitute for bone regeneration and repair.

Milestones and current achievements in development of multifunctional bioscaffolds for medical application

Tissue engineering (TE) is a rapidly growing interdisciplinary field, which aims to restore or improve lost tissue function. Despite that TE was introduced more than 20 years ago, innovative and more sophisticated trends and technologies point to new challenges and development. Current challenges involve the demand for multifunctional bioscaffolds which can stimulate tissue regrowth by biochemical curves, biomimetic patterns, active agents and proper cell types. For those purposes especially promising are carefully chosen primary cells or stem cells due to its high proliferative and differentiation potential. This review summarized a variety of recently reported advanced bioscaffolds which present new functions by combining polymers, nanomaterials, bioactive agents and cells depending on its desired application. In particular necessity of study biomaterial-cell interactions with in vitro cell culture models, and studies using animals with in vivo systems were discuss to permit the analysis of full material biocompatibility. Although these bioscaffolds have shown a significant therapeutic effect in nervous, cardiovascular and muscle, tissue engineering, there are still many remaining unsolved challenges for scaffolds improvement.

Microstructure Evolution and Mechanical Property Response of 3D-Printed Scalmalloy with Different Heat-Treatment Times at 325 °C

According to the material nature, aluminum alloys are widely applied in aerospace, construction, and automotive applications due to their characteristics of being lightweight, having good formability, and having good corrosion resistance. To further improve the degree of the lightweight quality, introducing a new material with high specific strength and a structure with a lightweight design would be efficient. Scalmalloy (Al-4.49Mg-0.71Sc-0.51Mn-0.27Zr-0.07Fe-0.03Si alloy), which exhibits high specific strength and is made by a 3D printing process with less design limitation, has huge application potential. In this study, the selective laser melting (SLM) process was introduced for sample preparation. Through XRD, EBSD, and TEM, the microstructure of the heat-treated samples at 325 °C with different heat-treatment times was analyzed to evaluate the optimized heat-treatment parameter for 3D printed Scalmalloy. The relationship between the mechanical properties and the variation of precipitation size and volume fraction is discussed in detail in this study.

Using a bio-scanner and 3D printing to create an innovative custom made approach for the management of complex entero-atmospheric fistulas

Enteroatmospheric fistulae are challenging clinical conditions that require surgical expertise and that can result in chronic debilitating conditions placing the patient in a vicious cycle characterized by non healing wounds and malnutrition. They are a complex entity that presents great variability depending on the number, shape, and size of the fistulous orifices, their debit, and the dimensions of the wound. This means that, at present, there is no device that adapts to the anatomical characteristics of each patient and manages to control the spillage of intestinal effluvium from the wound. The aim of this study is to describe the manufacturing technique and to assess the preliminary results of a custom device designed through bioscanner imaging and manufactured using 3D printing for use with negative pressure wound therapy (NPWT) in the management of enteroatmospheric fistula. A proof of concept is given, and the design of the device is presented for the first time. After obtaining images of each fistula with a bioscanner, a personalised device was designed for each patient by 3D printing shape of a prism and a hollow base, taking into account the dimensions of the fistulous area in order to perform a floating ostomy to isolate the wound from the debit enteric. The polycaprolactone (PCL) device was placed including inside the fistulous surface and surrounding it with the NPWT system in order to accelerate wound healing.

High-resolution electrohydrodynamic bioprinting: a new biofabrication strategy for biomimetic micro/nanoscale architectures and living tissue constructs

Electrohydrodynamic (EHD) printing is a newly emerging additive manufacturing strategy for the controlled fabrication of three-dimensional (3D) micro/nanoscale architectures. This unique superiority makes it particularly suitable for the biofabrication of artificial tissue analogs with biomimetic structural organizations similar to the scales of native extracellular matrix (ECM) or living cells, which shows great potentials to precisely regulate cellular behaviors and tissue regeneration. Here the state-of-the-art advancements of high-resolution EHD bioprinting were reviewed mainly including melt-based and solution-based processes for the fabrication of micro/nanoscale fibrous scaffolds and living tissues constructs. The related printing materials, innovations on structure design and printing processes, functionalization of the resultant architectures as well as their effects on the mechanical and biological properties of the EHD-printed structures were introduced and analyzed. The recent explorations on the EHD cell printing for high-resolution cell-laden microgel patterning and 3D construct fabrication were highlighted. The major challenges as well as possible solutions to translate EHD bioprinting into a mature and prevalent biofabrication strategy were finally discussed.

Bioactive Glasses and Glass/Polymer Composites for Neuroregeneration: Should We Be Hopeful?

Bioactive glasses (BGs) have been identified as highly versatile materials in tissue engineering applications; apart from being used for bone repair for many years, they have recently shown promise for the regeneration of peripheral nerves as well. They can be formulated in different shapes and forms (micro-/nanoparticles, micro-/nanofibers, and tubes), thus potentially meeting the diverse requirements for neuroregeneration. Mechanical and biological improvements in three-dimensional (3D) polymeric scaffolds could be easily provided by adding BGs to their composition. Various types of silicate, borate, and phosphate BGs have been examined for use in neuroregeneration. In general, BGs show good compatibility with the nervous system compartments both in vitro and in vivo. Functionalization and surface modification plus doping with therapeutic ions make BGs even more effective in peripheral nerve regeneration. Moreover, the combination of BGs with conductive polymers is suggested to improve neural cell functions at injured sites. Taking advantage of BGs combined with novel technologies in tissue engineering, like 3D printing, can open new horizons in reconstructive approaches for the nervous system. Although there are great potential opportunities in BG-based therapies for peripheral nerve regeneration, more research should still be performed to carefully assess the pros and cons of BGs in neuroregeneration strategies.