Micropatterned gellan gum-based hydrogels tailored with laminin-derived peptides for skeletal muscle tissue engineering

A biodegradable microgrooved and tissue mechanocompatible citrate-based scaffold improves bladder tissue regeneration

Chronic bladder dysfunction due to bladder disease or trauma is detrimental to affected patients as it can lead to increased risk of upper urinary tract dysfunction. Current treatment options include surgical interventions that enlarge the bladder with autologous bowel tissue to alleviate pressure on the upper urinary tract. This highly invasive procedure, termed bladder augmentation enterocystoplasty (BAE), significantly increases the risk of patient morbidity and mortality due to the incompatibility between bowel and bladder tissue. Therefore, patients would significantly benefit from an alternative treatment strategy that can regenerate healthy tissue and restore overall bladder function. Previous research has demonstrated the potential of citrate-based scaffolds co-seeded with bone marrow-derived stem/progenitor cells as an alternative graft for bladder augmentation. Recognizing that contact guidance can potentially influence tissue regeneration, we hypothesized that microtopographically patterned scaffolds would modulate cell responses and improve overall quality of the regenerated bladder tissue. We fabricated microgrooved (MG) scaffolds using the citrate-based biomaterial poly (1,8-octamethylene-citrate-co-octanol) (POCO) and co-seeded them with human bone marrow-derived mesenchymal stromal cells (MSCs) and CD34+ hematopoietic stem/progenitor cells (HSPCs). MG POCO scaffolds supported MSC and HSPC attachment, and MSC alignment within the microgrooves. All scaffolds were characterized and assessed for bladder tissue regeneration in an established nude rat bladder augmentation model. In all cases, normal physiological function was maintained post-augmentation, even without the presence of stem/progenitor cells. Urodynamic testing at 4-weeks post-augmentation for all experimental groups demonstrated that bladder capacity increased and bladder compliance was normal. Histological evaluation of the regenerated tissue revealed that cell-seeded scaffolds restored normal bladder smooth muscle content and resulted in increased revascularization and peripheral nerve regeneration. The presence of microgrooves on the cell-seeded scaffolds increased microvasculature formation by 20 % and urothelial layer thickness by 25 % in the regenerating tissue. Thus, this work demonstrates that microtopography engineering can influence bladder tissue regeneration to improve overall anatomical structure and re-establish bladder physiology.

Engineering Nanoclusters of Cell Adhesive Ligands on Biomaterial Surfaces: Superior Cell Proliferation and Myotube Formation for Skeletal Muscle Tissue Regeneration

Engineering biointerfaces with nanoscale clustering of integrin-binding cell adhesive peptides is critical for promoting receptor redistribution into signaling complexes. Skeletal muscle cells are exquisitely sensitive to integrin-mediated signaling, yet biomaterials supporting myogenesis through control of the density and nanodistribution of ligands have not been developed. Here, materials are developed with tailorable cell adhesive ligands distribution at the interface by independently controlling their global and local density to enhance myogenesis, by promoting myoblast growth and myotube formation. To this end, RGD-functionalized low-fouling polymer surfaces with global ligand densities (G) from 0-7 µg peptide/mg polymer and average local ligand densities (L) from 1-6.3 ligands/cluster, are generated and characterized. Cell studies demonstrate improvements in cell adhesion, spreading, growth, and myotube formation up to a density of 7 µg peptide/mg polymer with 4 ligands/cluster. Optimizing ligand density and distribution also promotes early myofiber maturation, identified by increased MF20 marker protein expression and sarcomere-forming myotubes. At higher ligand densities, these cell properties are decreased, indicating that ligand multivalency is a critical parameter for tailoring cell-material interactions, to a certain threshold. The findings provide new insights for designing next-generation biomaterials and hold promise for improved engineering of skeletal muscle.

A Novel Hydrogel Sponge for Three-Dimensional Cell Culture

BACKGROUND/OBJECTIVES

Three-dimensional (3D) cell culture technologies allow us to overcome the constraints of two-dimensional methods in different fields like biochemistry and cell biology and in pharmaceutical in vitro tests. In this study, a novel 3D hydrogel sponge scaffold, composed of a crosslinked polyacrylic acid forming a porous matrix, has been developed and characterized.

METHODS

The scaffold was obtained via an innovative procedure involving thermal treatment followed by a salt-leaching step on a matrix-containing polymer along with a gas-forming agent. Based on experimental design for mixtures, a series of formulations were prepared to study the effect of the three components (polyacrylic acid, NaHCO3 and NaCl) on the scaffold mechanical properties, density, swelling behavior and morphological changes. Physical appearance, surface morphology, porosity, molecular diffusion, transparency, biocompatibility and cytocompatibility were also evaluated.

RESULTS

The hydrogel scaffolds obtained show high porosity and good optical transparency and mechanical resistance. The scaffolds were successfully employed to culture several cell lines for more than 20 days.

CONCLUSIONS

The developed scaffolds could be an important tool, as such or with a specific coating, to obtain a more predictive cellular response to evaluate drugs in preclinical studies or for testing chemical compounds, biocides and cosmetics, thus reducing animal testing.

Multifaceted Hydrogel Scaffolds: Bridging the Gap between Biomedical Needs and Environmental Sustainability

Hydrogels are dynamically evolving 3D networks composed of hydrophilic polymer scaffolds with significant applications in the healthcare and environmental sectors. Notably, protein-based hydrogels mimic the extracellular matrix, promoting cell adhesion. Further enhancing cell proliferation within these scaffolds are matrix-metalloproteinase-triggered amino acid motifs. Integration of cell-friendly modules like peptides and proteins expands hydrogel functionality. These exceptional properties position hydrogels for diverse applications, including biomedicine, biosensors, environmental remediation, and the food industry. Despite significant progress, there is ongoing research to optimize hydrogels for biomedical and environmental applications further. Engineering novel hydrogels with favorable characteristics is crucial for regulating tissue architecture and facilitating ecological remediation. This review explores the synthesis, physicochemical properties, and biological implications of various hydrogel types and their extensive applications in biomedicine and environmental sectors. It elaborates on their potential applications, bridging the gap between advancements in the healthcare sector and solutions for environmental issues.

Towards more realistic cultivated meat by rethinking bioengineering approaches

Cultivated meat (CM) refers to edible lab-grown meat that incorporates cultivated animal cells. It has the potential to address some issues associated with real meat (RM) production, including the ethical and environmental impact of animal farming, and health concerns. Recently, various biomanufacturing methods have been developed to attempt to recreate realistic meat in the laboratory. We therefore overview recent achievements and challenges in the production of CM. We also discuss the issues that need to be addressed and suggest additional recommendations and potential criteria to help to bridge the gap between CM and RM from an engineering standpoint.

Bioactive Hydrogels Inspired by Laminin: An Emerging Biomaterial for Tissue Engineering Applications

Tissue or organ damage due to severe injuries or chronic diseases can adversely affect the quality of life. Current treatments rely on organ or tissue transplantation which has limitations including unavailability of donors, ethical issues, or immune rejection after transplantations. These limitations can be addressed by tissue regeneration which involves the development of bioactive scaffolds closely mimicking the extracellular matrix (ECM). One of the major components of ECM is the laminin protein which supports several tissues associated with important organs. In this direction, peptide-based hydrogels can effectively mimic the essential characteristics of laminin. While several reports have discussed the structure of laminin, the potential of laminin-derived peptide hydrogels as effective biomaterial for tissue engineering applications is yet to be discussed. In this context, the current review focuses on the structure of laminin and its role as an essential ECM protein. Further, the potential of short peptide hydrogels in mimicking the crucial properties of laminin is proposed. The review further highlights the significance of bioactive hydrogels inspired by laminin - in addressing numerous tissue engineering applications including angiogenesis, neural, skeletal muscle, liver, and adipose tissue regeneration along with a brief outlook on the future applications of these laminin-based hydrogels.

Advances in tissue engineering of gellan gum-based hydrogels

Gellan Gum (GG) is a large, naturally occurring, linear polysaccharide with a similar structure and biological properties to the extracellular matrix. It's appropriate as a matrix material for the development of different composite materials due to its biocompatibility, biodegradability, and injectability. Hydrogels made from GG have found various applications in the field of Tissue Engineering (TE) in recent years after being mixed with a variety of other organic and inorganic components. These composites are considered multifunctional developing biomaterials because of their impressive mechanical capabilities, biocompatibility, low cytotoxicity, etc. This review focuses on the emerging advances of GG-based hydrogels in TE, providing an overview of the applications of different types of GG-based composite materials in bone TE, cartilage TE, nervous TE, retina TE, and other fields. Moreover, the investigations of GG-based hydrogels as bioink components for 3D bioprinting in TE will be elucidated. This review offers general guidance for the development of biomaterials related to GG, as well as ideas for future clinical diagnosis and treatment.

Porous biomaterial scaffolds for skeletal muscle tissue engineering

Volumetric muscle loss is a traumatic injury which overwhelms the innate repair mechanisms of skeletal muscle and results in significant loss of muscle functionality. Tissue engineering seeks to regenerate these injuries through implantation of biomaterial scaffolds to encourage endogenous tissue formation and to restore mechanical function. Many types of scaffolds are currently being researched for this purpose. Scaffolds are typically made from either natural, synthetic, or conductive polymers, or any combination therein. A major criterion for the use of scaffolds for skeletal muscle is their porosity, which is essential for myoblast infiltration and myofiber ingrowth. In this review, we summarize the various methods of fabricating porous biomaterial scaffolds for skeletal muscle regeneration, as well as the various types of materials used to make these scaffolds. We provide guidelines for the fabrication of scaffolds based on functional requirements of skeletal muscle tissue, and discuss the general state of the field for skeletal muscle tissue engineering.

Peptide- and Metabolite-Based Hydrogels: Minimalistic Approach for the Identification and Characterization of Gelating Building Blocks

Minimalistic peptide- and metabolite-based supramolecular hydrogels have great potential relative to traditional polymeric hydrogels in various biomedical and technological applications. Advantages such as remarkable biodegradability, high water content, favorable mechanical properties, biocompatibility, self-healing, synthetic feasibility, low cost, easy design, biological function, remarkable injectability, and multi-responsiveness to external stimuli make supramolecular hydrogels promising candidates for drug delivery, tissue engineering, tissue regeneration, and wound healing. Non-covalent interactions such as hydrogen bonding, hydrophobic interactions, electrostatic interactions, and π-π stacking interactions play key roles in the formation of peptide- and metabolite-containing low-molecular-weight hydrogels. Peptide- and metabolite-based hydrogels display shear-thinning and immediate recovery behavior due to the involvement of weak non-covalent interactions, making them supreme models for the delivery of drug molecules. In the areas of regenerative medicine, tissue engineering, pre-clinical evaluation, and numerous other biomedical applications, peptide- and metabolite-based hydrogelators with rationally designed architectures have intriguing uses. In this review, we summarize the recent advancements in the field of peptide- and metabolite-based hydrogels, including their modifications using a minimalistic building-blocks approach for various applications.

Advances in Peptide-Based Hydrogel for Tissue Engineering

The development of peptide-based materials has emerged as one of the most challenging aspects of biomaterials in recent years. It has been widely acknowledged that peptide-based materials can be used in a broad range of biomedical applications, particularly in tissue engineering. Among them, hydrogels have been attracting considerable interest in tissue engineering because they mimic tissue formation conditions by providing a three-dimensional environment and a high water content. It has been found that peptide-based hydrogels have received more attention due to mimicking proteins, particularly extracellular matrix proteins, as well as the wide variety of applications they are capable of serving. It is without a doubt that peptide-based hydrogels have become the leading biomaterials of today owing to their tunable mechanical stability, high water content, and high biocompatibility. Here, we discuss in detail various types of peptide-based materials, emphasizing peptide-based hydrogels, and then we examine in detail how hydrogels are formed, paying particular attention to the peptide structures that are incorporated into the final structure. Following that, we discuss the self-assembly and formation of hydrogels under various conditions, as well as the parameters to be considered as critical factors, which include pH, amino acid composi- tion within the sequence, and cross-linking techniques. Further, recent studies on the development of peptide-based hydrogels and their applications in tissue engineering are reviewed.

Peptide-Based Hydrogels: New Materials for Biosensing and Biomedical Applications

Peptide-based hydrogels have attracted increasing attention for biological applications and diagnostic research due to their impressive features including biocompatibility and biodegradability, injectability, mechanical stability, high water absorption capacity, and tissue-like elasticity. The aim of this review will be to present an updated report on the advancement of peptide-based hydrogels research activity in recent years in the field of anticancer drug delivery, antimicrobial and wound healing materials, 3D bioprinting and tissue engineering, and vaccines. Additionally, the biosensing applications of this key group of hydrogels will be discussed mainly focusing the attention on cancer detection.

Multitasking smart hydrogels based on the combination of alginate and poly(3,4-ethylenedioxythiophene) properties: A review

Poly(3,4-ethylenedioxythiophene) (PEDOT), a very stable and biocompatible conducting polymer, and alginate (Alg), a natural water-soluble polysaccharide mainly found in the cell wall of various species of brown algae, exhibit very different but at the same complementary properties. In the last few years, the remarkable capacity of Alg to form hydrogels and the electro-responsive properties of PEDOT have been combined to form not only layered composites (PEDOT-Alg) but also interpenetrated multi-responsive PEDOT/Alg hydrogels. These materials have been found to display outstanding properties, such as electrical conductivity, piezoelectricity, biocompatibility, self-healing and re-usability properties, pH and thermoelectric responsiveness, among others. Consequently, a wide number of applications are being proposed for PEDOT-Alg composites and, especially, PEDOT/Alg hydrogels, which should be considered as a new kind of hybrid material because of the very different chemical nature of the two polymeric components. This review summarizes the applications of PEDOT-Alg and PEDOT/Alg in tissue interfaces and regeneration, drug delivery, sensors, microfluidics, energy storage and evaporators for desalination. Special attention has been given to the discussion of multi-tasking applications, while the new challenges to be tackled based on aspects not yet considered in either of the two polymers have also been highlighted.

3D bioprinting of gellan gum-based hydrogels tethered with laminin-derived peptides for improved cellular behavior

The treatment of skeletal muscle defects is still a topic of noteworthy concern since surgical intervention is not capable of recovering muscle function. Herein, we propose myoblasts laden in laminin-inspired biofunctionalized gellan gum hydrogels as promising tissue-engineered skeletal muscle surrogates. Gellan gum-based hydrogels were developed by combining native gellan gum (GG) and GG tethered with laminin-derived peptides (CIKVAVS (V), KNRLTIELEVRTC (T) or RKRLQVQLSIRTC (Q)), using different polymer content (0.75%-1.875%). Hydrogels were characterized in terms of compressive modulus, molecules trafficking, and C2C12 adhesion. Hydrogels with higher polymeric content (1.125%-1.875%) showed higher stiffness whereas hydrogels with lower polymer content (0.75%-1.125%) showed higher fluorescein isothiocyanate-dextran molecules diffusion. Cell spreading was achieved regardless of the laminin-derived peptide but preferred in hydrogels with higher polymer content (1.125%-1.875%). Taken together, hydrogels with 1.125% of polymer content were selected for printability analysis. GG-based inks showed a non-newtonian, shear-thinning, and thixotropic behavior suitable for printing. Accordingly, all inks were printable, but inks tethered with T and Q peptides presented some signs of clogging. Cell viability was affected after printing but increased after 7 days of culture. After 7 days, cells were spreading but not showing significant signs of cell-cell communications. Therefore, cell density was increased, thus, myocytes loaded in V-tethered GG-based inks showed higher cell-cell communication, spreading morphology, and alignment 7, 14 days post-printing. Overall, myoblasts laden in laminin-inspired biofunctionalized GG-based hydrogels are a promising skeletal muscle surrogate with the potential to be used as in vitro model or explored for further in vivo applications.

Injectable laminin-biofunctionalized gellan gum hydrogels loaded with myoblasts for skeletal muscle regeneration

Moderate muscular injuries that exceed muscular tissue's auto-healing capacity are still a topic of noteworthy concern. Tissue engineering appeared as a promising therapeutic strategy capable of overcoming this unmet clinical need. To attain such goal, herein we propose an in situ-crosslinking gellan gum (GG)-based hydrogel tethered with a skeletal muscle-inspired laminin-derived peptide RKRLQVQLSIRTC(Q) and encapsulated with skeletal muscle cells (SMCs). Pre-hydrogel solutions presented decreasing shear viscosity with increasing shear rate and shear stress, and required low forces for extrusion, validating their injectability. The GGDVS hydrogel was functionalized with Q-peptide with 30% of efficiency. C2C12 were able to adhere to the developed hydrogel, remained living and spreading 7 days post-encapsulation. Q-peptide release studies indicated that 25% of the unbound peptide can be released from the hydrogels up to 7 days, dependent on the hydrogel formulation. Treatment of a chemically-induced muscular lesion in mice with an injection of C2C12-laden hydrogels improved myogenesis, primarily promoted by the C2C12. In accordance, a high density of myoblasts (α-SA⁺ and MYH7⁺) were localized in tissues treated with the C2C12 (alone or encapsulated in the hydrogel). α-SA protein levels were significantly increased 8 weeks post-treatment with C2C12-laden hydrogels and MHC protein levels were increased in all experimental groups 4 weeks post-treatment, in relation to the SHAM. Neovascularization and neoinnervation was also detected in the defects. Altogether, this study indicates that C2C12-laden hydrogels hold great potential for skeletal muscle regeneration. STATEMENT OF SIGNIFICANCE: We developed an injectable gellan gum-based hydrogel for delivering C2C12 into localized myopathic model. The gellan gum was biofunctinalized with laminin-derived peptide to mimic the native muscular ECM. In addition, hydrogel was physically tuned to mimic the mechanical properties of native tissue. To the best of our knowledge, this formula was used for the first time under the context of skeletal muscle tissue regeneration. The injectability of the developed hydrogel provided non-invasive administration method, combined with a reliable microenvironment that can host C2C12 with nominal inflammation, indicated by the survival and adhesion of encapsulated cells post-injection. The treatment of skeletal muscle defect with the cell-laden hydrogel approach significantly enhanced the regeneration of localized muscular trauma.

Hydrogel supplemented with human platelet lysate enhances multi-lineage differentiation of mesenchymal stem cells

Stem cells from human exfoliated deciduous teeth (SHED) can be used as a potential clinical material. But the use of xenogeneic ingredients will increase the risk of zoonotic disease transmission. Human platelet lysate (HPL) is a potential surrogate and used in human cell expansion with reliability in clinical applications. In this study, we synthesized chitosan/gelatin/gellan gum hydrogel supplemented with HPL and investigated the effect of 3D culture for SHED. TMT-tagged proteomics was used to decipher the secretome protein profiles of SHEDs and a total of 3209 proteins were identified, of which 23 were up-regulated and 192 were down-regulated. The results showed that hydrogel supplemented with HPL promoted SHED proliferation. After induction, the hydrogel coating contributed to osteogenic differentiation, adipogenic differentiation and differentiation into neural-like cells of SHED. SHED encapsulated in a hydrogel promotes migration and angiogenesis of HUVEC. In conclusion, our research found that hydrogel supplemented with HPL can be used as a method for SHED in standardized production and can contribute to the clinical application of SHED in cell therapy.

Hydrogel-Based Fiber Biofabrication Techniques for Skeletal Muscle Tissue Engineering

The functional capabilities of skeletal muscle are strongly correlated with its well-arranged microstructure, consisting of parallelly aligned myotubes. In case of extensive muscle loss, the endogenous regenerative capacity is hindered by scar tissue formation, which compromises the native muscle structure, ultimately leading to severe functional impairment. To address such an issue, skeletal muscle tissue engineering (SMTE) attempts to fabricate in vitro bioartificial muscle tissue constructs to assist and accelerate the regeneration process. Due to its dynamic nature, SMTE strategies must employ suitable biomaterials (combined with muscle progenitors) and proper 3D architectures. In light of this, 3D fiber-based strategies are gaining increasing interest for the generation of hydrogel microfibers as advanced skeletal muscle constructs. Indeed, hydrogels possess exceptional biomimetic properties, while the fiber-shaped morphology allows for the creation of geometrical cues to guarantee proper myoblast alignment. In this review, we summarize commonly used hydrogels in SMTE and their main properties, and we discuss the first efforts to engineer hydrogels to guide myoblast anisotropic orientation. Then, we focus on presenting the main hydrogel fiber-based techniques for SMTE, including molding, electrospinning, 3D bioprinting, extrusion, and microfluidic spinning. Furthermore, we describe the effect of external stimulation (i.e., mechanical and electrical) on such constructs and the application of hydrogel fiber-based methods on recapitulating complex skeletal muscle tissue interfaces. Finally, we discuss the future developments in the application of hydrogel microfibers for SMTE.