Three-dimensional (3D) printing and 3D bioprinting are promising technologies for a broad range of healthcare applications from frontier regenerative medicine and tissue engineering therapies to ...pharmaceutical advancements yet must overcome the challenges of biocompatibility and resolution. Through comparison of traditional biofabrication methods with 3D (bio)printing, this review highlights the promise of 3D printing for the production of on-demand, personalized, and complex products that enhance the accessibility, effectiveness, and safety of drug therapies and delivery systems. In addition, this review describes the capacity of 3D bioprinting to fabricate patient-specific tissues and living cell systems (e.g., vascular networks, organs, muscles, and skeletal systems) as well as its applications in the delivery of cells and genes, microfluidics, and organ-on-chip constructs. This review summarizes how tailoring selected parameters (i.e., accurately selecting the appropriate printing method, materials, and printing parameters based on the desired application and behavior) can better facilitate the development of optimized 3D-printed products and how dynamic 4D-printed strategies (printing materials designed to change with time or stimulus) may be deployed to overcome many of the inherent limitations of conventional 3D-printed technologies. Comprehensive insights into a critical perspective of the future of 4D bioprinting, crucial requirements for 4D printing including the programmability of a material, multimaterial printing methods, and precise designs for meticulous transformations or even clinical applications are also given.
Biofabrication using well-matched cell/materials systems provides unprecedented opportunities for dealing with human health issues where disease or injury overtake the body’s native regenerative ...abilities. Such opportunities can be enhanced through the development of biomaterials with cues that appropriately influence embedded cells into forming functional tissues and organs. In this context, biomaterials’ reliance on rigid biofabrication techniques needs to support the incorporation of a hierarchical mimicry of local and bulk biological cues that mimic the key functional components of native extracellular matrix. Advances in synthetic self-assembling peptide biomaterials promise to produce reproducible mimics of tissue-specific structures and may go some way in overcoming batch inconsistency issues of naturally sourced materials. Recent work in this area has demonstrated biofabrication with self-assembling peptide biomaterials with unique biofabrication technologies to support structural fidelity upon 3D patterning. The use of synthetic self-assembling peptide biomaterials is a growing field that has demonstrated applicability in dermal, intestinal, muscle, cancer and stem cell tissue engineering.
A significant challenge to current cancer drug treatment is mode of delivery, both in terms of efficacy and off-target toxicity to healthy tissues. To overcome this, drug localisation using a range ...of biocompatible carriers is currently in use or under investigation. One class of these biomaterial carriers that offers a unique prospect for use as drug delivery vectors to tumour sites is hydrogels formed by small molecules. In particular, tissue mimetic self-assembling molecular hydrogels can function either as injectable precursors that gelate in response to tumour-specific markers, or as implants in conjunction with surgical resection or tumour debulking. Their inherent biocompatibility, tuneable properties, and capacity to flow and gelate
in situ
allow them to effectively transport, hold and release therapeutic molecules in a spatially and temporally controlled manner. This has been shown in a number of
in vitro
and
in vivo
studies, where they improve anti-cancer efficacy while reducing non-specific toxicity. However, further investigation is required to optimise these systems toward both the drug and the target tissue, to provide sophisticated temporal control over the drug presentation, and to determine the most effective drug-material combinations for specific cancer types and locations.
Self-assembling peptide hydrogels can effectively transport, hold and release therapeutic molecules in a spatially and temporally controlled manner and, in doing so, improve anti-cancer drug efficacy while reducing non-specific toxicity.
Metastatic tumours are complex ecosystems; a community of multiple cell types, including cancerous cells, fibroblasts, and immune cells that exist within a supportive and specific microenvironment. ...The interplay of these cells, together with tissue specific chemical, structural and temporal signals within a three-dimensional (3D) habitat, direct tumour cell behavior, a subtlety that can be easily lost in 2D tissue culture. Here, we investigate a significantly improved tool, consisting of a novel matrix of functionally programmed peptide sequences, self-assembled into a scaffold to enable the growth and the migration of multicellular lung tumour spheroids, as proof-of-concept. This 3D functional model aims to mimic the biological, chemical, and contextual cues of an in vivo tumor more closely than a typically used, unstructured hydrogel, allowing spatial and temporal activity modelling. This approach shows promise as a cancer model, enhancing current understandings of how tumours progress and spread over time within their microenvironment.
The debilitating effects of muscle damage, either through ischemic injury or volumetric muscle loss (VML), can have significant impacts on patients, and yet there are few effective treatments. This ...challenge arises when function is degraded due to significant amounts of skeletal muscle loss, beyond the regenerative ability of endogenous repair mechanisms. Currently available surgical interventions for VML are quite invasive and cannot typically restore function adequately. In response to this, many new bioengineering studies implicate 3D bioprinting as a viable option. Bioprinting for VML repair includes three distinct phases: printing and seeding, growth and maturation, and implantation and application. Although this 3D bioprinting technology has existed for several decades, the advent of more advanced and novel printing techniques has brought us closer to clinical applications. Recent studies have overcome previous limitations in diffusion distance with novel microchannel construct architectures and improved myotubule alignment with highly biomimetic nanostructures. These structures may also enhance angiogenic and nervous ingrowth post-implantation, though further research to improve these parameters has been limited. Inclusion of neural cells has also shown to improve myoblast maturation and development of neuromuscular junctions, bringing us one step closer to functional, implantable skeletal muscle constructs. Given the current state of skeletal muscle 3D bioprinting, the most pressing future avenues of research include furthering our understanding of the physical and biochemical mechanisms of myotube development and expanding our control over macroscopic and microscopic construct structures. Further to this, current investigation needs to be expanded from immunocompromised rodent and murine myoblast models to more clinically applicable human cell lines as we move closer to viable therapeutic implementation.
Gene delivery has been extensively investigated for introducing foreign genetic material into cells to promote expression of therapeutic proteins or to silence relevant genes. This approach can ...regulate genetic or epigenetic disorders, offering an attractive alternative to pharmacological therapy or invasive protein delivery options. However, the exciting potential of viral gene therapy has yet to be fully realized, with a number of clinical trials failing to deliver optimal therapeutic outcomes. Reasons for this include difficulty in achieving localized delivery, and subsequently lower efficacy at the target site, as well as poor or inconsistent transduction efficiency. Thus, ongoing efforts are focused on improving local viral delivery and enhancing its efficiency. Recently, biomaterials have been exploited as an option for more controlled, targeted and programmable gene delivery. There is a growing body of literature demonstrating the efficacy of biomaterials and their potential advantages over other delivery strategies. This review explores current limitations of gene delivery and the progress of biomaterial‐mediated gene delivery. The combination of biomaterials and gene vectors holds the potential to surmount major challenges, including the uncontrolled release of viral vectors with random delivery duration, poorly localized viral delivery with associated off‐target effects, limited viral tropism, and immune safety concerns.
Viral vector gene delivery using biomaterials holds the potential to address the range of challenges currently facing viral treatment. Using biomaterials as a biologically coherent delivery construct can achieve the controlled release and duration of viral gene delivery, localization of gene delivery, attenuation of immune response, modulation of viral tropism, providing efficient and long‐term gene expression.
Display omitted
Gene therapy offers hope for currently untreatable diseases; the patient’s own cellular machinery is recruited to create therapeutics. However, unpredictable responses that lead to ...neutralization by the host immune system and issues in constraining, controlling and sustaining delivery have presented clinical barriers to otherwise promising therapeutic developments. Here, we show that the protective environment provided by advanced biomaterials can function as injectable gene carriers to focus their therapeutic potential. Firstly, we investigated the potential of a tissue-specific molecular hydrogel to package recombinant adeno-associated viruses (rAAVs). Once a delivery pathway was confirmed, a set of rAAV variants were subsequently assessed for their ability to transduce various types of rodent and human neural cells in vitro and in vivo. Based on GFP expression, we identified a relatively new variant, rAAV-DJ, as showing desirable characteristics for constrained delivery and transduction efficiency. For the first time, we demonstrated precise control over the strength and type of interaction between biomaterials and rAAVs enabling the programmed release of viral payloads. This new approach enables specific infection of desired anatomical targets in a programmed fashion.
The survival and synaptic integration of transplanted dopaminergic (DA) progenitors are essential for ameliorating motor symptoms in Parkinson's disease (PD). Human pluripotent stem cell ...(hPSC)‐derived DA progenitors are, however, exposed to numerous stressors prior to, and during, implantation that result in poor survival. Additionally, hPSC‐derived grafts show inferior plasticity compared to fetal tissue grafts. These observations suggest that a more conducive host environment may improve graft outcomes. Here, tissue‐specific support to DA progenitor grafts is provided with a fully characterized self‐assembling peptide hydrogel. This biomimetic hydrogel matrix is programmed to support DA progenitors by i) including a laminin epitope within the matrix; and ii) shear encapsulating glial cell line‐derived neurotrophic factor (GDNF) to ensure its sustained delivery. The biocompatible hydrogel biased a 51% increase in A9 neuron specification—a subpopulation of DA neurons critical for motor function. The sustained delivery of GDNF induced a 2.7‐fold increase in DA neurons and enhanced graft plasticity, resulting in significant improvements in motor deficits at 6 months. These findings highlight the therapeutic benefit of stepwise customization of tissue‐specific hydrogels to improve the physical and trophic support of human PSC‐derived neural transplants, resulting in improved standardization, predictability and functional efficacy of grafts for PD.
The benefits of a functionalized tissue‐specific hydrogel are demonstrated to support human stem cell‐derived neural transplants in a Parkinson's disease model. The laminin epitope‐presenting hydrogel selectively supports A9 dopamine neurons, critical for motor function, while sustained glial cell line‐derived neurotrophic factor delivery enhances graft survival and plasticity—collectively resulting in improved recovery of motor symptoms.
Glioblastoma (GBM) is the most common and most aggressive primary brain tumour in adults, and its prognosis remains poor, with a near-universal fatality rate. This is due to a number of key obstacles ...in treating GBM, including: (i) the limited capacity for complete surgical resection due to risk of functional damage; (ii) the blood-brain barrier (BBB) preventing the systemic transport of many drugs into the brain, restricting treatment options; and (iii) the highly aggressive and infiltrative nature of GBM, which increases the likelihood of cancer cells remaining in the brain after treatment, responsible for high rates of recurrence.As such, one major avenue of interest for the improvement of GBM treatment outcomes is localised, post-operative drug delivery, to bypass the BBB and directly treat cells remaining at the resection margin. Biomaterials provide a promising vehicle for these delivery systems, due to their biocompatibility, biodegradability and capacity to mimic native tissue to support the area surrounding a surgical void. The overarching aim of this thesis is to develop a novel anticancer drug delivery system that, in conjunction with current surgical methods, may help to delay or prevent recurrence of GBM tumours. Using a tissue-specific self-assembling peptide (SAP) hydrogel as the delivery vehicle, here we developed an injectable and biocompatible drug delivery system that can be implanted post-operatively to release anticancer drugs directly at the site of resection.We demonstrate that the laminin-derived Fmoc-DDIKVAV SAP hydrogel used for neural applications has sequence-specific biocompatibility, supporting larger cell graft volumes with reduced immunoreactivity compared to alternative functional and non-functional sequences in the mouse brain in vivo. We also demonstrate that this Fmoc-DDIKVAV system is capable of supporting the culture of patient-derived GBM cell lines in vitro, maintaining cell viability and proliferation compared to the traditional 2D substrate used for GBM cell culture. We also show that the material's charge, and therefore the cellular response to the material, can be attenuated by altering the acid used to trigger self-assembly without affecting other key properties of the hydrogels.We show that three anticancer agents (CX-5461, PMR-116 and fucoidan) can be incorporated into the hydrogels without disrupting the hydrogel assembly mechanism or the anticancer activity of the drugs in GBM cells. In addition, we show that the method of drug incorporation has a major impact on the release rate of PMR-116, where release of shear encapsulated PMR-116 is approximately twice as fast as coassembled PMR-116 over 4 days. While both methods yield a linear release profile, this indicates that coassembly of drugs into the hydrogels provides the greatest potential for sustained release in the brain post-operatively.Collectively, these results demonstrate that Fmoc-SAP hydrogels are a promising material in the field of cancer research, both as a substrate for 3D culture of cancer cells and as an anticancer drug delivery vehicle for sustained, local drug release. This may help to improve treatment outcomes in GBM, bypassing the challenges posed by the BBB and reducing recurrence rates by treating cancer cells directly at the target site.
Tissue Programmed Hydrogels
In article number 2105301, David R. Nisbet, Clare L. Parish, and co‐workers show that encapsulating human stem cell‐derived dopamine progenitors within a neural tissue ...biomimetic hydrogel enhances their engraftment in an animal model of Parkinson's disease. The laminin‐based hydrogel, simultaneously sustains delivery of glial cell‐derived neurotrophic factor and increases dopamine neuron survival and their plasticity, and consequently the functional capacity of the graft to reverse motor deficits.
PDF
