BioMIPs: molecularly imprinted silk fibroin nanoparticles to recognize the iron regulating hormone hepcidin.

The possibility to prepare molecularly imprinted nanoparticles from silk fibroin was recently demonstrated starting from methacrylated silk fibroin and choosing a protein as template. Here, we attempted the imprinting of fibroin-based molecularly imprinted polymers (MIPs), called bioMIPs, using as a template hepcidin that is a iron-metabolism regulator-peptide, possessing a hairpin structure. A homogeneous population (PDI < 0.2) of bioMIPs with size ~50 nm was produced. The bioMIPs were selective for the template; the estimated dissociation constant for hepcidin was KD = 3.6 ± 0.5 10-7 M and the average number of binding sites per bioMIP was equal to 2. The bioMIPs used in a competitive assay for hepcidin in serum showed a detection range of 1.01 10-7- 6.82 10-7 M and a limit of detection of 3.29 10-8 M.

Wharton's jelly-derived mesenchymal cells as a new source for the generation of microtissues for tissue engineering applications.

Microtissues (MT) are currently considered as a promising alternative for the fabrication of natural, 3D biomimetic functional units for the construction of bio-artificial substitutes by tissue engineering (TE). The aim of this study was to evaluate the possibility of generating mesenchymal cell-based MT using human umbilical cord Wharton's jelly stromal cells (WJSC-MT). MT were generated using agarose microchips and evaluated ex vivo during 28 days. Fibroblasts MT (FIB-MT) were used as control. Morphometry, cell viability and metabolism, MT-formation process and ECM synthesis were assessed by phase-contrast microscopy, functional biochemical assays, and histological analyses. Morphometry revealed a time-course compaction process in both MT, but WJSC-MT resulted to be larger than FIB-MT in all days analyzed. Cell viability and functionality evaluation demonstrated that both MT were composed by viable and metabolically active cells, especially the WJSC during 4-21 days ex vivo. Histology showed that WJSC acquired a peripheral pattern and synthesized an extracellular matrix-rich core over the time, what differed from the homogeneous pattern observed in FIB-MT. This study demonstrates the possibility of using WJSC to create MT containing viable and functional cells and abundant extracellular matrix. We hypothesize that WJSC-MT could be a promising alternative in TE protocols. However, future cell differentiation and in vivo studies are still needed to demonstrate the potential usefulness of WJSC-MT in regenerative medicine.

Bone mineral density affects tumor growth by shaping microenvironmental heterogeneity.

Breast cancer bone metastasis is a major cause of mortality in patients with advanced breast cancer. Although decreased mineral density is a known risk factor for bone metastasis, the underlying mechanisms remain poorly understood because studying the isolated effect of bone mineral density on tumor heterogeneity is challenging with conventional approaches. Moreover, mineralized biomaterials are commonly utilized for clinical bone defect repair, but how mineralized biomaterials affect the foreign body response and wound healing is unclear. Here, we investigate how bone mineral affects tumor growth and microenvironmental complexity in vivo by combining single-cell RNA-sequencing with mineral-containing or mineral-free decellularized bone matrices. We discover that the absence of bone mineral significantly influences fibroblast and immune cell heterogeneity, promoting phenotypes that increase tumor growth and alter the response to injury or disease. Importantly, we observe that the stromal response to bone mineral content depends on the murine tumor model used. While lack of bone mineral induces tumor-promoting microenvironments in both immunocompromised and immunocompetent animals, these changes are mediated by altered fibroblast phenotype in immunocompromised mice and macrophage polarization in immunocompetent mice. Collectively, our findings suggest that bone mineral density affects tumor growth by impacting microenvironmental complexity in an organism-dependent manner.

Collagen sponge scaffolds loaded with Trichostatin A pretreated BMSCs-derived exosomes regulate macrophage polarization to promote skin wound healing.

The process of wound healing includes the inflammatory stage, which plays an important role. Macrophages can promote inflammatory response and also promote angiogenesis, wound contraction and tissue remodeling required for wound healing. It is crucial to promote macrophages to polarize from M1 pro-inflammatory phenotype to M2 anti-inflammatory phenotype at a critical time for the quality of wound healing. Because mesenchymal stem cell-derived exosomes have broad therapeutic prospects in the field of tissue repair and regeneration, in this study, we explored whether trichostatin A pretreated bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (T-Exo) could promote wound healing by binding to biomaterial scaffolds through certain anti-inflammatory effects. In the cell experiment, we established macrophage inflammation model and then treated with T-Exo, and finally detected the expression levels of macrophage polarization proteins CD206, CD86 and TNF-α, iNOS, and Arg-1 by Western Blot and immunofluorescence staining; detected the expression levels of inflammation-related genes TNF-α, iNOS, IL-1ß, IL-10 and anti-inflammatory genes CD206 and Arg-1 by qRT-PCR; explored the promoting ability of T-Exo to promote cell migration and tube formation by cell scratch experiment and angiogenesis experiment. The results showed that T-Exo could promote the polarization of M1 macrophages to M2 macrophages, and promote the migration and angiogenesis of HUVECs. Because TSA pretreatment may bring about changes in the content and function of BMSCs-derived exosomes, proteomic analysis was performed on T-Exo and unpretreated BMSCs-derived exosomes (Exo). The results showed that the differentially expressed proteins in T-Exo were related to some pathways that promote angiogenesis, cell migration, proliferation, and re-epithelialization. Then, exosome/collagen sponge (T-Exo/Col) biological scaffolds were prepared, and the physicochemical properties and biocompatibility of the scaffolds were investigated. Animal skin wound models were established, and the therapeutic effect and anti-inflammatory effect of T-Exo/Col in wound repair were evaluated by small animal in vivo imaging, H&E staining, Masson trichrome staining, immunohistochemical staining, Western Blot, and qRT-PCR. The results showed that T-Exo significantly promoted wound healing by inhibiting inflammation, thereby further promoting angiogenesis and collagen formation in vivo. Moreover, the existence of Col scaffold in T-Exo/Col enabled T-Exo to achieve a certain sustained release effect. Finally, we further explored whether TSA exerts beneficial effects by inhibiting HDAC6 gene of BMSCs, but the results showed that knockdown of HDAC6 gene would cause oxidative stress damage to BMSCs, which means that TSA does not produce these beneficial effects by inhibiting HDAC6 gene. What molecular mechanisms TSA exerts beneficial effects through needs to be further elucidated in the future.

Bilayer scaffold from PLGA/fibrin electrospun membrane and fibrin hydrogel layer supports wound healingin vivo.

Hybrid scaffolds from natural and synthetic polymers have been widely used due to the complementary nature of their physical and biological properties. The aim of the present study, therefore, has been to analyzein vivoa bilayer scaffold of poly(lactide-co-glycolide)/fibrin electrospun membrane and fibrin hydrogel layer on a rat skin model. Fibroblasts were cultivated in the fibrin hydrogel layer and keratinocytes on the electrospun membrane to generate a skin substitute. The scaffolds without and with cells were tested in a full-thickness wound model in Wistar Kyoto rats. The histological results demonstrated that the scaffolds induced granulation tissue growth, collagen deposition and epithelial tissue remodeling. The wound-healing markers showed no difference in scaffolds when compared with the positive control. Activities of antioxidant enzymes were decreased concerning the positive and negative control. The findings suggest that the scaffolds contributed to the granulation tissue formation and the early collagen deposition, maintaining an anti-inflammatory microenvironment.

Biomimetic natural biomaterials for tissue engineering and regenerative medicine: new biosynthesis methods, recent advances, and emerging applications.

Biomimetic materials have emerged as attractive and competitive alternatives for tissue engineering (TE) and regenerative medicine. In contrast to conventional biomaterials or synthetic materials, biomimetic scaffolds based on natural biomaterial can offer cells a broad spectrum of biochemical and biophysical cues that mimic the in vivo extracellular matrix (ECM). Additionally, such materials have mechanical adaptability, microstructure interconnectivity, and inherent bioactivity, making them ideal for the design of living implants for specific applications in TE and regenerative medicine. This paper provides an overview for recent progress of biomimetic natural biomaterials (BNBMs), including advances in their preparation, functionality, potential applications and future challenges. We highlight recent advances in the fabrication of BNBMs and outline general strategies for functionalizing and tailoring the BNBMs with various biological and physicochemical characteristics of native ECM. Moreover, we offer an overview of recent key advances in the functionalization and applications of versatile BNBMs for TE applications. Finally, we conclude by offering our perspective on open challenges and future developments in this rapidly-evolving field.

Different Species of Marine Sponges Diverge in Osteogenic Potential When Therapeutically Applied as Natural Scaffolds for Bone Regeneration in Rats.

A highly porous structure, and an inorganic (biosilica) and collagen-like organic content (spongin) makes marine sponges potential candidates to be used as natural scaffolds in bone tissue engineering. The aim of this study was to characterize (through SEM, FTIR, EDS, XRD, pH, mass degradation and porosity tests) scaffolds produced from two species of marine sponges, Dragmacidon reticulatum (DR) and Amphimedon viridis (AV), and to evaluate the osteogenic potential of these scaffolds by using a bone defect model in rats. First, it was shown that the same chemical composition and porosity (84 ± 5% for DR and 90 ± 2% for AV) occurs among scaffolds from the two species. Higher material degradation was observed in the scaffolds of the DR group, with a greater loss of organic matter after incubation. Later, scaffolds from both species were surgically introduced in rat tibial defects, and histopathological analysis after 15 days showed the presence of neo-formed bone and osteoid tissue within the bone defect in DR, always around the silica spicules. In turn, AV exhibited a fibrous capsule around the lesion (19.9 ± 17.1%), no formation of bone tissue and only a small amount of osteoid tissue. The results showed that scaffolds manufactured from Dragmacidon reticulatum presented a more suitable structure for stimulation of osteoid tissue formation when compared to Amphimedon viridis marine sponge species.

Applications of the amniotic membrane in tissue engineering and regeneration: the hundred-year challenge.

The amniotic membrane (Amnio-M) has various applications in regenerative medicine. It acts as a highly biocompatible natural scaffold and as a source of several types of stem cells and potent growth factors. It also serves as an effective nano-reservoir for drug delivery, thanks to its high entrapment properties. Over the past century, the use of the Amnio-M in the clinic has evolved from a simple sheet for topical applications for skin and corneal repair into more advanced forms, such as micronized dehydrated membrane, amniotic cytokine extract, and solubilized powder injections to regenerate muscles, cartilage, and tendons. This review highlights the development of the Amnio-M over the years and the implication of new and emerging nanotechnology to support expanding its use for tissue engineering and clinical applications.

Preparation and evaluation of a silk fibroin-polycaprolactone biodegradable biomimetic tracheal scaffold.

In tracheal tissue engineering, the construction of tracheal scaffolds with adequate biodegradable mechanical capacity and biological functions that mimic the structure of a natural trachea is challenging. To explore the feasibility of preparing biomimetic degradable scaffolds with C-type cartilage rings and an inner tracheal wall of polycaprolactone and silk fibroin. A mold was made according to the diameter of a rabbit trachea, and a silk fibroin tube and polycaprolactone ring attached to the tube were obtained by solution casting. The ring was fixed to the tube at a specific spacing using electrostatic spinning technology to construct a biomimetic tracheal scaffold; its porous structure was observed by scanning electron microscopy, its degradation properties were determined by in vitro enzymatic hydrolysis and its mechanical properties were obtained by pressure testing. The composite scaffold was transplanted subcutaneously into a rabbit model, and the scaffold was taken at 1, 2, and 4 weeks after surgery for sectioning to observe pre-vascularization. The Medical Ethics Committee of Guangdong Provincial People's Hospital approved the study. The general view of the biomimetic scaffold: the polycaprolactone ring was fixed firmly on the outer wall of the silk fibroin tube; the two corresponded in size, and they fitted closely. The surface of the polycaprolactone ring was smooth and dense, while the surface of the silk fibroin tube could be seen as a uniform porous structure. Scanning electron microscopy showed that the surface and profile of the fibroin tube had a uniform pore size and distribution. The pores were connected to form a network. In vitro, enzymatic hydrolysis experiments confirmed that the fibroin was degraded easily, with most being degraded at the end of week 1. The degradation slowed at 2, 3, and 4 weeks, while the degradation of polycaprolactone was extremely slow. A compression test showed that the compressive resistance of the silk fibroin-polycaprolactone biomimetic scaffolds was much better than that of the rabbit trachea at close thickness. In the tissue staining experiments, as the material degraded, fibrous tissues and blood vessels grew to replace the material, allowing the scaffold to obtain a blood supply and better mechanical properties. A quantitative analysis of CD31 showed that the results for the vascularization of the scaffold were better at 4 weeks than at 2 weeks following subcutaneous grafting (P < .05). The results confirmed that it is feasible to prepare porous, degradable silk fibroin-polycaprolactone biomimetic scaffolds with good mechanical properties and epithelial biological functions by mold casting.

Nanoscale Calcium Salt-Based Formulations As Potential Therapeutics for Osteoporosis.

Osteoporosis causes severe bone damage, posing potential risks to human health, patient quality of life, and society. Calcium has been widely shown to enhance bone density and prevent osteoporosis-related bone fractures. Here, we focused on calcium salt formulations containing natural substances and their possible therapeutic effects on osteoporosis. In particular, we developed a nanoscale calcium salt of natural origin and formulated nanocomposite tablets supplemented with vitamin D (Vit D), herb Rhodiola rosea (R. rosea) and natural mineral Shilajit that are known to be antiosteoporotic. The calcium salt nanocomposites exhibited no toxicity, and particularly the formulation containing R. rosea stimulated osteogenic differentiation. The calcium salt nanocomposites inhibited osteoclastic activity, including RANKL expression, as shown by a decrease in tartrate-resistant acid phosphatase (TRAP)-positive cells. When administered orally to osteoporotic rats for 45 days, the calcium salt nanocomposites reduced bone resorption, as evidenced by the significantly higher bone volume and density, increase in osteoblasts and decrease in osteoclasts compared to those in nontreated control rats. Systemic administration of the nanocomposites caused no severe stomach toxicity or damage over the test period, during which no renal stone growth was observed. On the basis of their significant bilateral effects in stimulating osteoblasts and inhibiting osteoclasts and the resultant efficacy in an osteoporotic model, the nanocomposite tablets composed of a calcium salt and natural products can be considered novel nanotherapeutics for osteoporosis treatment.

Natural-Based Biomaterials for Peripheral Nerve Injury Repair.

Peripheral nerve injury treatment is a relevant problem because of nerve lesion high incidence and because of unsatisfactory regeneration after severe injuries, thus resulting in a reduced patient's life quality. To repair severe nerve injuries characterized by substance loss and to improve the regeneration outcome at both motor and sensory level, different strategies have been investigated. Although autograft remains the gold standard technique, a growing number of research articles concerning nerve conduit use has been reported in the last years. Nerve conduits aim to overcome autograft disadvantages, but they must satisfy some requirements to be suitable for nerve repair. A universal ideal conduit does not exist, since conduit properties have to be evaluated case by case; nevertheless, because of their high biocompatibility and biodegradability, natural-based biomaterials have great potentiality to be used to produce nerve guides. Although they share many characteristics with synthetic biomaterials, natural-based biomaterials should also be preferable because of their extraction sources; indeed, these biomaterials are obtained from different renewable sources or food waste, thus reducing environmental impact and enhancing sustainability in comparison to synthetic ones. This review reports the strengths and weaknesses of natural-based biomaterials used for manufacturing peripheral nerve conduits, analyzing the interactions between natural-based biomaterials and biological environment. Particular attention was paid to the description of the preclinical outcome of nerve regeneration in injury repaired with the different natural-based conduits.

Natural Biomaterials for Cardiac Tissue Engineering: A Highly Biocompatible Solution.

Cardiovascular diseases (CVD) constitute a major fraction of the current major global diseases and lead to about 30% of the deaths, i.e., 17.9 million deaths per year. CVD include coronary artery disease (CAD), myocardial infarction (MI), arrhythmias, heart failure, heart valve diseases, congenital heart disease, and cardiomyopathy. Cardiac Tissue Engineering (CTE) aims to address these conditions, the overall goal being the efficient regeneration of diseased cardiac tissue using an ideal combination of biomaterials and cells. Various cells have thus far been utilized in pre-clinical studies for CTE. These include adult stem cell populations (mesenchymal stem cells) and pluripotent stem cells (including autologous human induced pluripotent stem cells or allogenic human embryonic stem cells) with the latter undergoing differentiation to form functional cardiac cells. The ideal biomaterial for cardiac tissue engineering needs to have suitable material properties with the ability to support efficient attachment, growth, and differentiation of the cardiac cells, leading to the formation of functional cardiac tissue. In this review, we have focused on the use of biomaterials of natural origin for CTE. Natural biomaterials are generally known to be highly biocompatible and in addition are sustainable in nature. We have focused on those that have been widely explored in CTE and describe the original work and the current state of art. These include fibrinogen (in the context of Engineered Heart Tissue, EHT), collagen, alginate, silk, and Polyhydroxyalkanoates (PHAs). Amongst these, fibrinogen, collagen, alginate, and silk are isolated from natural sources whereas PHAs are produced via bacterial fermentation. Overall, these biomaterials have proven to be highly promising, displaying robust biocompatibility and, when combined with cells, an ability to enhance post-MI cardiac function in pre-clinical models. As such, CTE has great potential for future clinical solutions and hence can lead to a considerable reduction in mortality rates due to CVD.

Autologous Fractionated Adipose Tissue as a Natural Biomaterial and Novel One-Step Stem Cell Therapy for Repairing Articular Cartilage Defects.

Articular cartilage damage remains a tough challenge for clinicians. Stem cells have emerged promising biologics in regenerative medicine. Previous research has widely demonstrated that adipose-derived mesenchymal stem cells (ADSCs) can promote cartilage repair due to their multipotency. However, enzymatic isolation and monolayer expansion of ADSCs decrease their differentiation potential and limit their clinical application. Here, a novel adipose tissue-derived product, extracellular matrix/stromal vascular fraction gel (ECM/SVF-gel), was obtained by simple mechanical shifting and centrifugation to separate the fat oil and concentrate the effective constituents. This study aimed to evaluate the therapeutic effect of this natural biomaterial on the repair of articular cartilage defects. Scanning electron microscopy showed that the fibrous structure in the ECM/SVF-gel was preserved. ADSCs sprouted from the ECM/SVF-gel were characterized by their ability of differentiation into chondrocytes, osteoblasts, and adipocytes. In a rabbit model, critical-sized cartilage defects (diameter, 4 mm; depth, 1.5 mm) were created and treated with microfracture (MF) or a combination of autologous ECM/SVF-gel injection. The knee joints were evaluated at 6 and 12 weeks through magnetic resonance imaging, macroscopic observation, histology, and immunohistochemistry. The International Cartilage Repair Society score and histological score were significantly higher in the ECM/SVF-gel group than those in the MF-treated group. The ECM/SVF-gel distinctly improved cartilage regeneration, integration with surrounding normal cartilage, and the expression of hyaline cartilage marker, type II collagen, in comparison with the MF treatment alone. Overall, the ready-to-use ECM/SVF-gel is a promising therapeutic strategy to facilitate articular cartilage regeneration. Moreover, due to the simple, time-sparing, cost-effective, enzyme-free, and minimally invasive preparation process, this gel provides a valuable alternative to stem cell-based therapy for clinical translation.

Cartography of the mechanical properties of the human amniotic membrane.

Because of its low immunogenicity, biological properties, and high availability, the Human Amniotic Membrane (HAM) is widely used in the clinic and in tissue engineering research. However, while its biological characteristics are well described, its mechanical properties remain understudied especially in terms of inter- and intra-HAM variability. To guide bioengineers in the use of this natural biomaterial, a detailed cartography of the HAM's mechanical properties was performed. Maximal force (Fmax) and strain at break (Smax) were identified as the relevant mechanical criteria for this study after a combined analysis of histological sections, thickness measurements after dehydration, and uniaxial tensile tests. Eight HAMs were studied by mechanical cartography using a standardized cutting protocol and sampling pattern. On average, 103 ±â€¯10 samples were retrieved and tested per HAM. Intra-tissue variability highlighted the fact that there were two mechanically distinct areas (placental and peripheral) in each HAM. For all HAMs, placental HAM was significantly stronger by 82 ±â€¯45% and more stretchable by 19 ±â€¯6% than their peripheral counterparts. Our results also demonstrated that placental, but not peripheral, HAM presented isotropic mechanical properties. Thus, placental HAM can be a raw material of choice that could be favored especially in the development of tissue engineering products where mechanical properties play a key role.

Advanced Carbon for Flexible and Wearable Electronics.

Flexible and wearable electronics are attracting wide attention due to their potential applications in wearable human health monitoring and care systems. Carbon materials have combined superiorities such as good electrical conductivity, intrinsic and structural flexibility, light weight, high chemical and thermal stability, ease of chemical functionalization, as well as potential mass production, enabling them to be promising candidate materials for flexible and wearable electronics. Consequently, great efforts are devoted to the controlled fabrication of carbon materials with rationally designed structures for applications in next-generation electronics. Herein, the latest advances in the rational design and controlled fabrication of carbon materials toward applications in flexible and wearable electronics are reviewed. Various carbon materials (carbon nanotubes, graphene, natural-biomaterial-derived carbon, etc.) with controlled micro/nanostructures and designed macroscopic morphologies for high-performance flexible electronics are introduced. The fabrication strategies, working mechanism, performance, and applications of carbon-based flexible devices are reviewed and discussed, including strain/pressure sensors, temperature/humidity sensors, electrochemical sensors, flexible conductive electrodes/wires, and flexible power devices. Furthermore, the integration of multiple devices toward multifunctional wearable systems is briefly reviewed. Finally, the existing challenges and future opportunities in this field are summarized.

Resistive Switching Memory Devices Based on Body Fluid of Bombyx mori L.

Resistive switching memory devices are strong candidates for next-generation data storage devices. Biological memristors made from renewable natural biomaterials are very promising due to their biocompatibility, biodegradability, and ecological benignity. In this study, a nonvolatile memristor was fabricated using the body fluid of Bombyx mori as the dielectric layer. The developed Al/Bombyx mori body fluid film/indium tin oxide (ITO) biomemristor exhibited bipolar resistive switching characteristics with a maximum on/off current ratio greater than 104. The device showed a retention time of more than 1 × 104 s without any signs of deterioration, thus proving its good stability and reliability. The resistive switching behavior of the Al/Bombyx mori body fluid film/ITO biological memristor is driven by the formation and breakage of conductive filaments formed by the migration of oxygen ions. This study confirms that Bombyx mori body fluid, a 100% natural, inexpensive, and abundant material, is a potential candidate as a nonvolatile biomemristor material with broad application prospects.

A Cell-Engineered Small Intestinal Submucosa-Based Bone Mimetic Construct for Bone Regeneration.

Extracellular matrix (ECM)-ornamented biomaterials have attracted attention due to their high potential to improve the biofunctionality of original materials. It is thought that ECM with a bone mimetic microenvironment generated by the specific induction of osteoblasts would be more beneficial for bone regeneration than a regular ECM. In this study, we developed an osteogenic and mineralized ECM construct (Os/M-ECM-SIS) under the guidance of osteoblasts on a small intestinal submucosa (SIS) scaffold cotreated with icariin and calcium. The generated Os/M-ECM-SIS scaffolds exhibited similar morphology and inorganic components as natural bone and higher mechanical strength than ECM-SIS. Cell adhesion, proliferation, and differentiation of osteoblasts and fibroblasts were also enhanced in the cells cultured on the Os/M-ECM-SIS scaffolds. The Os/M-ECM-SIS scaffolds even promoted transdifferentiation of fibroblasts with an upregulation of osteogenic differentiation markers. In a calvarial defect model, new bone formation was greatly enhanced in defects implanted with the Os/M-ECM-SIS scaffolds compared with ECM-SIS scaffolds. Further study showed that the Os/M-ECM-SIS scaffolds promoted bone regeneration in vitro and in vivo via the Bmp/Smad-signaling pathway. Thus, this work proposes a valuable method for generating a mineralized bone mimetic scaffold with SIS as off-the-shelf bone graft substitute that provides an excellent osteogenic microenvironment, making it suitable for application in bone tissue engineering.