Natural melanin nanoparticles (MNPs) extracted from Sepia officinalis: A cost-effective, chemo-photothermal, synergistic nanoplatform for osteosarcoma treatment.

Osteosarcoma conventional chemotherapeutics are known for their side effects, limited options, and induction of drug resistance. This creates the need to develop new therapeutics capable of effectively destroying cancer cells with low toxicity, improving patient survival rate and their life quality. This work reports a novel drug delivery nanoplataform made of Natural Melanin Nanoparticles (MNPs), obtained from Sepia officinalis ink, with 99% incorporation efficiency of doxorubicin (Dox) without the use of non-toxic solvents. A significant photothermal effect was shown by a 36ºC increment after 10 min of laser irradiation, surpassing reported values for synthetic melanin. A sustained drug release of ca. 23% with photothermal stimuli was observed, compared to 15% without stimuli, after 48 h. This nanoplatform is obtained as a food industry side product, which makes it a natural cost-effective biomedical material. Natural MPs were applied in an osteosarcoma cell line (SaOs-2), and internalized by the cells in less than 2 h, showing cytocompatibility up to 1000 µg/mL after 72 h of contact with cells. On the contrary, when natural MNPs loaded with Dox (Dox-MNPs) were placed in contact with the SaOs-2 cells and were simultaneously receiving NIR light it was observed a 93% reduction in cancer cells in 48 h, revealing a synergistic effect between chemotherapy and phototherapy. To our knowledge this is the first time that natural MNPs extracted from Sepia officinalis were tested on an osteosarcoma cell line as chemo-photothermal agent, showing these NPs are an effective, cost-effective, reproducible, non-toxic nanoplatform for osteosarcoma treatment using combined effects.

Human adipose-derived mesenchymal stem cells laden in gellan gum spongy-like hydrogels for volumetric muscle loss treatment.

BACKGROUND: volumetric muscle loss (VML) is a traumatic massive loss of muscular tissue which frequently leads to amputation, limb loss, or lifetime disability. The current medical intervention is limited to autologous tissue transfer, which usually leads to non-functional tissue recovery. Tissue engineering holds a huge promise for functional recovery. METHODS: in this work, we evaluated the potential of human adipose-derived mesenchymal stem cells (hASCs) pre-cultured in gellan gum based spongy-like hydrogels (SLHs). RESULTS: in vitro, hASCs were spreading, proliferating, and releasing growth factors and cytokines (i.e. fibroblast growth factor, hepatocyte growth factor, insulin-like growth factor 1, interleukin-6 (IL-6), IL-8, IL-10, vascular endothelial growth factor) important for muscular regeneration. After implantation into a volumetric muscle loss (VML) mouse model, implants were degrading overtime, entirely integrating into the host between 4 and 8 weeks. In both SLH and SLH + hASCs defects, infiltrated cells were observed inside constructs associated with matrix deposition. Also, minimal collagen deposition was marginally observed around the constructs along both time-points. Neovascularization (CD31+vessels) and neoinnervation (ß-III tubulin+bundles) were significantly detected in the SLH + hASCs group, in relation to the SHAM (empty lesion). A higher density ofα-SA+and MYH7+cells were found in the injury site among all different experimental groups, at both time-points, in relation to the SHAM. The levels ofα-SA, MyoD1, and myosin heavy chain proteins were moderately increased in the SLH + hASCs group after 4 weeks, and in the hASCs group after 8 weeks, in relation to the SHAM. CONCLUSIONS: taken together, defects treated with hASCs-laden SLH promoted angiogenesis, neoinnervation, and the expression of myogenic proteins.

Recent advances in nanomaterial-based optical biosensors for food safety applications: Ochratoxin-A detection, as case study.

Global population growth tremendously impacts the global food industry, endangering food safety and quality. Mycotoxins, particularly Ochratoxin-A (OTA), emerge as a food chain production threat, since it is produced by fungus that contaminates different food species and products. Beyond this, OTA exhibits a possible human toxicological risk that can lead to carcinogenic and neurological diseases. A selective, sensitive, and reliable OTA biodetection approach is essential to ensure food safety. Current detection approaches rely on accurate and time-consuming laboratory techniques performed at the end of the food production process, or lateral-flow technologies that are rapid and on-site, but do not provide quantitative and precise OTA concentration measurements. Nanoengineered optical biosensors arise as an avant-garde solution, providing high sensing performance, and a fast and accurate OTA biodetection screening, which is attractive for the industrial market. This review core presents and discusses the recent advancements in optical OTA biosensing, considering engineered nanomaterials, optical transduction principle and biorecognition methodologies. Finally, the major challenges and future trends are discussed, and current patented OTA optical biosensors are emphasized for a particular promising detection method.

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.

Biosensors Advances: Contributions to Cancer Diagnostics and Treatment.

Cancer is the second leading cause of death worldwide, and its survival rate is significantly affected by early detection and treatment. However, most current diagnostic methods are symptoms oriented, and detecting cancer only in advanced phases. The few existent screening methods, such as mammograms and papanicolaou tests are invasive and not continuous, resulting in a high percentage of non-detected cancers in the early phases. Thus, there is an urgent need to create technologies that make cancer diagnostics more accessible to populations, enabling continuous or semi-continuous, noninvasive, "long-term" screening of cancer in high-risk patients and the whole population. Biosensors are being developed to create technologies that can be applied to point-of-care, wearable, and implantable diagnostics, aiming to fill this important gap in cancer early detection, and, therefore, increase the cancer rate of survival and reduce its morbidity. The versatility of these technologies, due to their miniaturization and diverse detection modes, will enable great advances in cancer early detection, since they can be adapted to the patient and its context, allowing personalized medicine to become a reality.

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.

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

The efficacy of current therapies for skeletal muscle disorders/injuries are limited urging the need for new treatments. Skeletal muscle tissue engineered platforms represent a promising tool to shed light on the pathophysiology of skeletal muscle disorders/injuries and to investigate the efficacy of new therapies. Herein, we developed a skeletal muscle platform composed of aligned and differentiated myoblasts on micropatterned gellan gum (GG)-based hydrogels tailored with a laminin-derived peptide. To this aim, the binding of murine skeletal muscle cells (C2C12) to different laminin-derived peptides (CIKVAVS (V), KNRLTIELEVRTC (T), and RKRLQVQLSIRTC (Q)) and the binding of laminin-derived peptides to chemically functionalized GG was studied. C2C12-binding to peptide V, T and Q was 10%, 48% and 25%, whereas the peptide tethering to GG was 60%, 40% and 31%, respectively. Peptide-biofunctionalized hydrogels prepared with different polymer content showed different mechanics and peptide exposure at hydrogel surface. Cellular adhesion was detected in all hydrogel formulations, but spreading and differentiation was only promoted in peptide Q-biofunctionalized hydrogels and preferably in stiffer hydrogels. Myoblast alignment was promoted in micropatterned hydrogel surfaces. Overall, the engineered skeletal muscle herein proposed can be further explored as a platform to better understand skeletal muscle disorders/injuries and to screen new therapies.

Tumor-Associated Protrusion Fluctuations as a Signature of Cancer Invasiveness.

The generation of invasive fluctuating protrusions is a distinctive feature of tumor dissemination. During the invasion, individual cancer cells modulate the morphodynamics of protrusions to optimize their migration efficiency. However, it remains unclear how protrusion fluctuations govern the invasion of more complex multi-cellular structures, such as tumors, and their correlation with the tumor metastatic potential. Herein, a reductionist approach based on 3D tumor cell micro-spheroids with different invasion capabilities is used as a model to decipher the role of tumor-associated fluctuating protrusions in cancer progression. To quantify fluctuations, a set of key biophysical parameters that precisely correlate with the invasive potential of tumors is defined. It is shown that different pharmacological drugs and cytokines are capable of modulating protrusion activity, significantly altering protrusion fluctuations, and tumor invasiveness. This correlation is used to define a novel quantitative invasion index encoding the key biophysical parameters of fluctuations and the relative levels of cell-cell/matrix interactions, which is capable of assessing the tumor's metastatic capability solely based on its magnitude. Overall, this study provides new insights into how protrusion fluctuations regulate tumor cell invasion, suggesting that they may be employed as a novel early indicator, or biophysical signature, of the metastatic potential of tumors.

adipoSIGHT in Therapeutic Response: Consequences in Osteosarcoma Treatment.

Chemotherapeutic resistance is a major problem in effective cancer treatment. Cancer cells engage various cells or mechanisms to resist anti-cancer therapeutics, which results in metastasis and the recurrence of disease. Considering the cellular heterogeneity of cancer stroma, the involvement of stem cells is reported to affect the proliferation and metastasis of osteosarcoma. Hence, the duo (osteosarcoma: Saos 2 and human adipose-derived stem cells: ASCs) is co-cultured in present study to investigate the therapeutic response using a nonadherent, concave surface. Staining with a cell tracker allows real-time microscopic monitoring of the cell arrangement within the sphere. Cell-cell interaction is investigated by means of E-cadherin expression. Comparatively high expression of E-cadherin and compact organization is observed in heterotypic tumorspheres (Saos 2-ASCs) compared to homotypic ones (ASCs), limiting the infiltration of chemotherapeutic compound doxorubicin into the heterotypic tumorsphere, which in turn protects cells from the toxic effect of the chemotherapeutic. In addition, genes known to be associated with drug resistance, such as SOX2, OCT4, and CD44 are overexpressed in heterotypic tumorspheres post-chemotherapy, indicating that the duo collectively repels the effect of doxorubicin. The interaction between ASCs and Saos 2 in the present study points toward the growing oncological risk of using ASC-based regenerative therapy in cancer patients and warrants further investigation.

Electro-responsive controlled drug delivery from melanin nanoparticles.

Electro-responsive controlled drug delivery has been receiving an increasing interest as one of the on-demand drug delivery systems, aiming the improvement of the therapeutics efficacy by controlling the amount of drug release at a specific time and target site. Herein, we report a simple method to develop an electro-responsive controlled drug delivery system using functionalized melanin nanoparticles (FMNPs) with polydopamine and polypyrrole to precisely control the release of dexamethasone (Dex). Optimized FMNPs showed 376.77 ± 62.05 nm of particle size, a polydispersity index of 0.26 ± 0.09 and a zeta-potential (ZP) of -32.59 ± 3.61 mV. FMNPs evidenced a spherical shape, which was confirmed by scanning electron microscopy. Fourier-transform infrared spectrometry analysis confirmed the deposition of the polymers on the FMNPs' surface. The incorporation efficiency of the optimized Dex-loaded FMNPs was 94.45 ± 0.63% and the increase of ZP to -40.34 ± 4.65 mV was attributed to the anionic nature of Dex. In vitro Dex release studies without stimuli revealed a maximum Dex release below 10%. Applying electrical stimulation, Dex release was augmented, with a maximum of ca. 32% after 24 h. The designed FMNPs provide a powerful biomaterial-based technological tool for electro-responsive controlled drug delivery, capable of surpassing the associated lack of efficiency and stability of current carriers.

Melanin nanoparticles as a promising tool for biomedical applications - a review.

Melanin is a biopolymer of easy and cheap availability that can be found among the living organisms and excels for its biocompatibility and biodegradability properties, along with scavenging abilities, metal chelation and electronic conductance. This biomaterial can act as a nanocarrier or agent itself to be used in diverse biomedical applications, such as imaging, controlled drug release, bioengineering and bioelectronics, antioxidant applications and theranostics. In this review, the melanin source and structure, its physicochemical properties, melanin-like polymers as well as the differences among those will be elucidated. The focus will be the discussion of the current approaches that apply melanin nanoparticles (MNPs) and melanin-like nanoparticles (MLNPs) in the biomedical field, to which promising capabilities have been attributed, regarding optoelectronic, photoconductivity and photoacoustic. The use of these nanoparticles, in the last 10 years, in topics as drug delivery or theranostics will be detailed and the major achievements will be discussed. Overall, we anticipate that melanin can drive us toward a new paradigm in medical diagnostics and treatments, since applying melanin features possibly its use as a theranostics nanocarrier agent, not only for diagnostics, but also for photothermal therapy and controlled drug release through chemotherapy. STATEMENT OF SIGNIFICANCE: We present here a timely and opportune review article focusing the significant potential of melanin nanoparticles in biomedical applications, which will be discussed thoroughly. This biomaterial presents multiple capabilities that may be taken into consideration towards cancer theranostics, expecting a high future impact in the nanosized-platforms design and performance.

Gene expression changes are associated with severe bone loss and deficient fracture callus formation in rats with complete spinal cord injury.

STUDY DESIGN: Animal study. OBJECTIVES: To investigate the effects of SCI on bone quality and callus formation. SETTING: University and hospital-based research center, Ribeirão Preto Medical School, Brazil. METHODS: Rats sustaining a complete SCI for 10 days received a fracture at the femoral diaphysis and were followed-up for 14 days. Bone callus and contralateral nonfractured tibia were assessed by DXA, µCT, ELISA, histomorphometry, immunohistochemistry, biomechanical test, and gene expression. RESULTS: SCI downregulated osteoblastic-related gene expression in the nonfractured tibias, associated with a twofold increase in osteoclasts and overexpression of RANK/RANKL, which resulted in lower bone mass, impaired microarchitecture, and weaker bones. On day 14 postfracture, we revealed early and increased trabecular formation in the callus of SCI rats, despite a marked 75% decrease in OPG-positive cells, and 41% decrease in density. Furthermore, these calluses showed higher porosity and thinner newly formed trabeculae, leading to lower strength and angle failure. CONCLUSIONS: SCI-induced bone loss resulted from increased bone resorption and decreased bone formation. We also evidenced accelerated bone healing in the SCI rats, which may be attributed to the predominant intramembranous ossification. However, the newly formed bone was thinner, less dense, and more porous than those in the non-SCI rats. As a result, these calluses are weaker and tolerate lesser torsion deformation than the controls, which may result in recurrent fractures and characterizes a remarkable feature that may severely impair life quality.

Improved vascularisation but inefficient in vivo bone regeneration of adipose stem cells and poly-3-hydroxybutyrate-co-3-hydroxyvalerate scaffolds in xeno-free conditions.

Bone defects are a common clinical situation. However, bone regeneration remains a challenge and faces the limitation of poor engraftment due to deficient vascularisation. Poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHB-HV) and human adipose stem cells (hASC) are promising for vascularisation and bone regeneration. Therefore, we sought to investigate the bone regenerative capacity of hASCs cultured in allogeneic human serum (aHS) and PHB-HV scaffolds in a nude mouse model of the critical-sized calvarial defect. We evaluated bone healing for three treatment groups: empty (control), PHB-HV and PHB-HV + hASCs. The pre-implant analysis showed that hASCs colonised the PHB-HV scaffolds maintaining cell viability before implantation. Histological analysis revealed that PHB-HV scaffolds were tolerated in vivo; they integrated with adjacent tissue eliciting a response like a foreign body reaction, and tiny primary bone was observed only in the PHB-HV group. Also, the µ-CT analysis revealed only approximately 10% of new bone in the bone defect area in both the PHB-HV and PHB-HV + hASCs groups. The expression of BGLAP and its protein (osteocalcin) by PHB-HV + hASCs group and native bone was similar while the other bone markers RUNX2, ALPL and COL1A1 were upregulated, but this expression remained significantly lower compared to the native bone. Nevertheless, the PHB-HV group showed neovascularisation at 12 weeks post-implantation while PHB-HV + hASCs group also exhibited higher VEGFA expression as well as a higher number of vessels at 4 weeks post-implantation, and, consequently, earlier neovascularisation. This neovascularisation must be due to scaffold architecture, improved by hASCs, that survived for the long term in vivo in the PHB-HV + hASCs group. These results demonstrated that hASCs cultured in aHS combined with PHB-HV scaffolds were ineffective to promote bone regeneration, although the construct of hASCs + PHB-HV in xeno-free conditions improved scaffold vascularisation representing a strategy potentially promising for other tissue engineering applications.

3D biosensors in advanced medical diagnostics of high mortality diseases.

Cardiovascular diseases, cancer, and diabetes are high mortality diseases, which account for almost two thirds of all deaths worldwide. Their early detection and continuous evaluation are fundamental for an improved patient prognosis and reduced socioeconomic impact. Current biosensor technologies are typically based on the analysis of whole blood samples from patients for the detection of disease-specific biomarkers. However, these technologies display serious shortcomings, such as reduced sensitivity and dynamic range, limited in vivo applicability, and lack of continuous monitoring. There is the urgent need for new diagnostic and treatment follow-up tools, which allow for the early detection of the pathology as well as for the continuous monitoring of the physiological responses to specific therapies. During the last years, a new generation of biosensor technologies with improved performance has emerged in the biomedical sector. The combination of advanced biomaterial methods, biochemical tools, and micro/nanotechnology approaches has resulted in the development of innovative three-dimensional (3D) biosensor platforms for advanced medical diagnosis. In this review, we report the most recent advances in the field of 3D biosensors for clinical applications, focusing on the diagnosis and monitoring of cardiovascular diseases, cancer, and diabetes. We discuss about their clinical performance compared to standard biosensor technologies, their implantable capability, and their integration into microfluidic devices to develop clinically-relevant models. Overall, we anticipate that 3D biosensors will drive us toward a new paradigm in medical diagnosis, resulting in real-time in vivo biosensors capable to significantly improve patient prognosis.

Differentiation of osteoclast precursors on gellan gum-based spongy-like hydrogels for bone tissue engineering.

Bone tissue engineering with cell-scaffold constructs has been attracting a lot of attention, in particular as a tool for the efficient guiding of new tissue formation. However, the majority of the current strategies used to evaluate novel biomaterials focus on osteoblasts and bone formation, while osteoclasts are often overlooked. Consequently, there is limited knowledge on the interaction between osteoclasts and biomaterials. In this study, the ability of spongy-like gellan gum and hydroxyapatite-reinforced gellan gum hydrogels to support osteoclastogenesis was investigated in vitro. First, the spongy-like gellan gum and hydroxyapatite-reinforced gellan gum hydrogels were characterized in terms of microstructure, water uptake and mechanical properties. Then, bone marrow cells isolated from the long bones of mice and cultured in spongy-like hydrogels were treated with 1,25-dihydroxyvitamin D3 to promote osteoclastogenesis. It was shown that the addition of HAp to spongy-like gellan gum hydrogels enables the formation of larger pores and thicker walls, promoting an increase in stiffness. Hydroxyapatite-reinforced spongy-like gellan gum hydrogels support the formation of the aggregates of tartrate-resistant acid phosphatase-stained cells and the expression of genes encoding DC-STAMP and Cathepsin K, suggesting the differentiation of bone marrow cells into pre-osteoclasts. The hydroxyapatite-reinforced spongy-like gellan gum hydrogels developed in this work show promise for future use in bone tissue scaffolding applications.

Emerging tumor spheroids technologies for 3D in vitro cancer modeling.

Cancer is a leading cause of mortality and morbidity worldwide. Around 90% of deaths are caused by metastasis and just 10% by primary tumor. The advancement of treatment approaches is not at the same rhythm of the disease; making cancer a focal target of biomedical research. To enhance the understanding and prompts the therapeutic delivery; concepts of tissue engineering are applied in the development of in vitro models that can bridge between 2D cell culture and animal models, mimicking tissue microenvironment. Tumor spheroid represents highly suitable 3D organoid-like framework elucidating the intra and inter cellular signaling of cancer, like that formed in physiological niche. However, spheroids are of limited value in studying critical biological phenomenon such as tumor-stroma interactions involving extra cellular matrix or immune system. Therefore, a compelling need of tailoring spheroid technologies with physiologically relevant biomaterials or in silico models, is ever emerging. The diagnostic and prognostic role of spheroids rearrangements within biomaterials or microfluidic channel is indicative of patient management; particularly for the decision of targeted therapy. Fragmented information on available in vitro spheroid models and lack of critical analysis on transformation aspects of these strategies; pushes the urge to comprehensively overview the recent technological advancements (e.g. bioprinting, micro-fluidic technologies or use of biomaterials to attain the third dimension) in the shed of translationable cancer research. In present article, relationships between current models and their possible exploitation in clinical success is explored with the highlight of existing challenges in defining therapeutic targets and screening of drug efficacy.

* Synthesis and Characterization of Electroactive Gellan Gum Spongy-Like Hydrogels for Skeletal Muscle Tissue Engineering Applications.

Advances on materials' research for tissue engineering (TE) applications have shown that animal cells respond directly to the material physical, chemical, mechanical, and electrical stimuli altering a variety of cell signaling cascades, which consequently result in phenotypic and genotypic alterations. Gellan gum (GG) spongy-like hydrogels (SLH) with open microstructure, mechanical properties, and cell performance have shown promising results for soft TE applications. Taking advantage of intrinsic properties of GG-SLH and polypyrrole (PPy) electroactivity, we developed electroactive PPy-GG-SLH envisaging their potential use for skeletal muscle TE. Three different methods of in situ chemical oxidative polymerization were developed based on the availability of pyrrole: freely dissolved in solution (method I and III) or immobilized into GG hydrogels (method II). PPy was homogeneously distributed within (method I and III) and on the surface (method II) of GG-SLH, as also confirmed by Fourier Transform infrared spectra. PPy-GG-SLH showed higher conductivity than GG-SLH (p < 0.05) whereas PPy-GG-SLH (method I and II) showed the best conductivity among the 3 methods (∼1 to 2 × 10-4 S/cm). The microarchitecture of PPy-GG-SLH (method I) was similar to GG-SLH but PPy-GG-SLH (method II and III) presented smaller pore sizes and lower porosity. PPy-GG-SLH (method I and II) compressive modulus (∼450-500 KPa) and recovering capacity (∼75-90%) was higher than GG-SLH, nevertheless the mechanical properties of PPy-GG-SLH (method III) were lower. The water uptake of PPy-GG-SLH was rapidly up to 2500% and were stable along 60 days of degradation being the maximum weight loss 20%. Mechanically stable and electroactive PPy-GG-SLH (method I and II) were analyzed regarding cellular performance. PPy-GG-SLH were not cytotoxic for L929 cells. In addition, L929 and C2C12 myoblast cells were able to adhere and spread within PPy-GG-SLH, showing improved spreading in comparison to GG-SLH performance. Overall, PPy-GG-SLH show promising features as an alternative electroactive platform to analyze the influence of electrical stimulation on skeletal muscle cells.

Anti-Cancer Drug Validation: the Contribution of Tissue Engineered Models.

Drug toxicity frequently goes concealed until clinical trials stage, which is the most challenging, dangerous and expensive stage of drug development. Both the cultures of cancer cells in traditional 2D assays and animal studies have limitations that cannot ever be unraveled by improvements in drug-testing protocols. A new generation of bioengineered tumors is now emerging in response to these limitations, with potential to transform drug screening by providing predictive models of tumors within their tissue context, for studies of drug safety and efficacy. Considering the NCI60, a panel of 60 cancer cell lines representative of 9 different cancer types: leukemia, lung, colorectal, central nervous system (CNS), melanoma, ovarian, renal, prostate and breast, we propose to review current "state of art" on the 9 cancer types specifically addressing the 3D tissue models that have been developed and used in drug discovery processes as an alternative to complement their study.

Evaluating Biomaterial- and Microfluidic-Based 3D Tumor Models.

Cancer is a major cause of morbidity and mortality worldwide, with a disease burden estimated to increase over the coming decades. Disease heterogeneity and limited information on cancer biology and disease mechanisms are aspects that 2D cell cultures fail to address. Here, we review the current 'state-of-the-art' in 3D tissue-engineering (TE) models developed for, and used in, cancer research. We assess the potential for scaffold-based TE models and microfluidics to fill the gap between 2D models and clinical application. We also discuss recent advances in combining the principles of 3D TE models and microfluidics, with a special focus on biomaterials and the most promising chip-based 3D models.

Polyhydroxybutyrate-co-hydroxyvalerate structures loaded with adipose stem cells promote skin healing with reduced scarring.

Currently available skin substitutes are still associated with a range of problems including poor engraftment resulting from deficient vascularization, and excessive scar formation, among others. Trying to overcome these issues, this work proposes the combination of poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) structures with adipose-derived stem cells (ASCs) to offer biomechanical and biochemical signaling cues necessary to improve wound healing in a full-thickness model. PHBV scaffold maintained the wound moisture and demonstrated enough mechanical properties to withstand wound contraction. Also, exudate and inflammatory cell infiltration enhanced the degradation of the structure, and thus healing progression. After 28 days all the wounds were closed and the PHBV scaffold was completely degraded. The transplanted ASCs were detected in the wound area only at day 7, correlating with an up-regulation of VEGF and bFGF at this time point that consequently led to a significant higher vessel density in the group that received the PHBV loaded with ASCs. Subsequently, the dermis formed in the presence of the PHBV loaded with ASCs possesses a more complex collagen structure. Additionally, an anti-scarring effect was observed in the presence of the PHBV scaffold indicated by a down-regulation of TGF-ß1 and α-SMA together with an increase of TGF-ß3, when associated with ASCs. These results indicate that although PHBV scaffold was able to guide the wound healing process with reduced scarring, the presence of ASCs was crucial to enhance vascularization and provide a better quality neo-skin. Therefore, we can conclude that PHBV loaded with ASCs possesses the necessary bioactive cues to improve wound healing with reduced scarring.