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%â 1.875%). Hydrogels were characterized in terms of compressive modulus, molecules trafficking, and C2C12 adhesion. Hydrogels with higher polymeric content (1.125%â 1.875%) showed higher stiffness whereas hydrogels with lower polymer content (0.75%â 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%â 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 7â days of culture. After 7â days, cells were spreading but not showing significant signs of cellâ cell communications. Therefore, cell density was increased, thus, myocytes loaded in V-tethered GG-based inks showed higher cellâ cell communication, spreading morphology, and alignment 7, 14â 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.CEEC Individual, Grant/Award Number: 2020.01541.CEECIND/CP1600/CT0024; Fundacao para a Ciencia e a Tecnologia, Grant/Award Number: PD/BD/128090/201

Micropatterned silk-fibroin/eumelanin composite films for bioelectronic applications

There has been growing interest in the use of natural bionanomaterials and nanostructured systems for diverse biomedical applications. Such materials can confer unique functional properties as well as address concerns pertaining to sustainability in production. In this work, we propose the biofabrication of micropatterned silk fibroin/eumelanin composite thin films to be used in electroactive and bioactive applications in bioelectronics and biomedical engineering. Eumelanin is the most common form of melanin, naturally derived from the ink of cuttlefish, having antioxidant and electroactive properties. Another natural biomaterial, the protein silk fibroin, is modified with photoreactive chemical groups, which allows the formation of electroactive eumelanin thin films with different microstructures. The silk fibroin/eumelanin composites are fabricated to obtain thin films as well as electroactive microstructures using UV curing. Here, we report for the first time the preparation, characterization, and physical, electrochemical, and biological properties of these natural silk fibroin/eumelanin composite films. Higher concentrations of eumelanin incorporated into the films exhibit a higher charge storage capacity and good electroactivity even after 100 redox cycles. In addition, the microscale structure and the cellular activity of the fibroin/eumelanin films are assessed for understanding of the biological properties of the composite. The developed micropatterned fibroin/eumelanin films can be applied as natural electroactive substrates for bioapplications (e.g., bioelectronics, sensing, and theranostics) because of their biocompatible properties.The authors acknowledge the FRONTHERA project (Frontiers of technology for theranostics of cancer, metabolic and neurodegenerative diseases) n degrees NORTE-01-0145-FEDER0000232, the European Union Framework Programme for Research and Innovation Horizon 2020 under grant agreement n degrees 668983. FoReCaST (Forefront Research in 3D Disease Cancer Models as in vitro Screening Technologies), and FCT grants POCI-01-0145-FEDER-031590, PD/BD/150546/2019 and PTDC/BTM-ORG/28168/2017. VKY acknowledges support from the National Science Foundation (CBET1704435)

Mechanomodulatory biomaterials prospects in scar prevention and treatment

Scarring is a major clinical issue that affects a considerable number of patients. The associated problems go beyond the loss of skin functionality, as scars bring aesthetic, psychological, and social difficulties. Therefore, new strategies are required to improve the process of healing and minimize scar formation. Research has highlighted the important role of mechanical forces in the process of skin tissue repair and scar formation, in addition to the chemical signalling. A more complete understanding of how engi- neered biomaterials can modulate these mechanical stimuli and modify the mechanotransduction signals in the wound microenvironment is expected to enable scar tissue reduction. The present review aims to provide an overview of our current understanding of skin biomechanics and mechanobiology underlying wound healing and scar formation, with an emphasis on the development of novel mechanomodulatory wound dressings with the capacity to offload mechanical tension in the wound environment. Further- more, a broad overview of current challenges and future perspectives of promising mechanomodulatory biomaterials for this application are provided.The authors would like to acknowledge Portuguese Foun dation for Science and Technology (FCT) for funding the research project Dressing4Scars M-ERA-NET2/0013/2016, and LP da Silva (2020.01541.CEECIND/CP1600/CT0024), and to Norte-01-0145-FEDER-02219015 (MT Cerqueira)

Integrin-specific hydrogels for growth factor-free vasculogenesis

Integrin-binding biomaterials have been extensively evaluated for their capacity to enable de novo formation of capillary-like structures/vessels, ultimately supporting neovascularization in vivo. Yet, the role of integrins as vascular initiators in engineered materials is still not well understood. Here, we show that αvβ3 integrin-specific 3D matrices were able to retain PECAM1+ cells from the stromal vascular fraction (SVF) of adipose tissue, triggering vasculogenesis in vitro in the absence of extrinsic growth factors. Our results suggest that αvβ3-RGD-driven signaling in the formation of capillary-like structures prevents the activation of the caspase 8 pathway and activates the FAK/paxillin pathway, both responsible for endothelial cells (ECs) survival and migration. We also show that prevascularized αvβ3 integrin-specific constructs inosculate with the host vascular system fostering in vivo neovascularization. Overall, this work demonstrates the ability of the biomaterial to trigger vasculogenesis in an integrin-specific manner, by activating essential pathways for EC survival and migration within a self-regulatory growth factor microenvironment. This strategy represents an improvement to current vascularization routes for Tissue Engineering constructs, potentially enhancing their clinical applicability.The authors would like to acknowledge the financial support from the Consolidator Grant “ECM_INK” (ERC-2016-COG-726061) and the Starting Grant “CapBed” (ERC2018-STG-805411), to the FSE/POCH (Fundo Social Europeu através do Programa Operacional do Capital Humano) under the scope of the PD/169/2013, NORTE-08- 5369-FSE-000037 (H.R.M.), and to FCT/MCTES (Fundação para a Ciência e a Tecnologia/ Ministério da Ciência, Tecnologia, e Ensino Superior) through the grants SFRH/BD/119756/2016 (D.B.R.), Ph.D. grant PD/BD/135252/2017 (S.F.R.) and IF/00347/ 2015 (R.P.P.)

Spongy-like hydrogels prevascularization with the adipose tissue vascular fraction delays cutaneous wound healing by sustaining inflammatory cell influx

In vitro prevascularization is one of the most explored approaches to foster engineered tissue vascularization. We previously demonstrated a benefit in tissue neovascularization by using integrin-specific biomaterials prevascularized by stromal vascular fraction (SVF) cells, which triggered vasculogenesis in the absence of extrinsic growth factors. SVF cells are also associated to biological processes important in cutaneous wound healing. Thus, we aimed to investigate whether in vitro construct prevascularization with SVF accelerates the healing cascade by fostering early vascularization vis-à-vis SVF seeding prior to implantation. Prevascularized constructs delayed re-epithelization of full-thickness mice wounds compared to both non-prevascularized and control (no SVF) groups. Our results suggest this delay is due to a persistent inflammation as indicated by a significantly lower M2(CD163+)/M1(CD86+) macrophage subtype ratio. Moreover, a slower transition from the inflammatory to the proliferative phase of the healing was confirmed by reduced extracellular matrix deposition and increased presence of thick collagen fibers from early time-points, suggesting the prevalence of fiber crosslinking in relation to neodeposition. Overall, while prevascularization potentiates inflammatory cell influx, which negatively impacts the cutaneous wound healing cascade, an effective wound healing was guaranteed in non-prevascularized SVF cell-containing spongy-like hydrogels confirming that the SVF can have enhanced efficacy.Authors would like to acknowledge the financial support from the Consolidator Grant “ECM_INK” (ERC-2016-COG-726061) and the Starting Grant “CapBed” (ERC-2018-STG-805411), to the FSE/POCH (Fundo Social Europeu através do Programa Operacional do Capital Humano) under the scope of the PD/169/2013, NORTE-08-5369-FSE-000037 (H.R.M.), and to FCT/MCTES (Fundação para a Ciência e a Tecnologia/ Ministério da Ciência, Tecnologia, e Ensino Superior) through the grants SFRH/BD/119756/2016 (D.B.R.), PhD grant PD/BD/135252/2017 (S.F.R.) and IF/00347/2015 (R.P.P.). Authors would also like to acknowledge BioRender.com as a platform for image creation

Os interiores domésticos após a expansão da economia exportadora paulista

The present article aims at describing São Paulo city dwellings and at studying its trade and crafts production in the first half of the 19th Century. Our work is chiefly based on information collected from post-mortem inventories registered in São Paulo capital city. Memorialists have described São Paulo city and its market as insignificant until coffee cultivation took over as the main economic activity. However, our research has found out that, on the contrary, the domestic trade had been very active since the beginning of the 19th century.Este artigo se propõe a descrever os interiores domésticos dos paulistanos e a refletir sobre o comércio e a produção artesanal da cidade de São Paulo na primeira metade do Oitocentos. Baseamo-nos principalmente nas informações dos inventários post-mortem da capital. Os memorialistas descreveram a cidade e seu mercado acanhados até o advento do café. Nossa pesquisa, ao contrário, identificou-os muito ativo desde o início do século XIX

Tailoring gellan gum spongy-like hydrogels’ microstructure by controlling freezing parameters

The following are available online at http://www.mdpi.com/2073-4360/12/2/329/s1, Figure S1: Freezing profiles of 0.75% GG hydrogels, Figure S2: Effect of freezing conditions (standard method, NFD, and IFD at −20, −80, and −210 ◦C) over the properties of 0.75% GG dried polymeric structures and spongy-like hydrogels., Figure S3: Water uptake of 1.25% GG spongy-like hydrogels at −20, −80, and −210 ◦C using different freezing systems, Figure S4: Scaffolds reproducibility, Figure S5: Effect of freezing conditions (standard method, NFD, and IFD at −20, −80, and −210 ◦C) over hDFb behavior in 0.75% GG spongy-like hydrogels.Gellan gum (GG) spongy-like hydrogels have been explored for different tissue engineering (TE) applications owing to their highly attractive hydrogel-like features, and improved mechanical resilience and cell performance. Although the whole process for the preparation of these materials is well-defined, we hypothesized that variations occurring during the freezing step lead to batch-to-batch discrepancies. Aiming to address this issue, two freezing devices were tested, to prepare GG spongy-like hydrogels in a more reproducible way. The cooling and freezing rates, the nucleation time and temperature, and the end freezing time were determined at different freezing temperatures (−20, −80, and −210 °C). The efficacy of the devices was assessed by analyzing the physicochemical, mechanical, and biological properties of different formulations. The cooling rate and freezing rate varied between 0.1 and 128 °C/min, depending on the temperature used and the device. The properties of spongy-like hydrogels prepared with the tested devices showed lower standard deviation in comparison to those prepared with the standard process, due to the slower freezing rate of the hydrogels. However, with this method, mean pore size was significantly lower than that with the standard method. Cell entrapment, adhesion, and viability were not affected as demonstrated with human dermal fibroblasts. This work confirmed that batch-to-batch variations are mostly due to the freezing step and that the tested devices allow fine tuning of the scaffolds’ structure and properties.This research was funded by UIDB/50026/2020 Co- financiado pelo Orçamento do Estado do Ministério da Ciência, Tecnologia e Ensino Superior e, por verbas do Fundo Social Europeu através dos Programas Operacionais Regionais do Portugal 2020.The authors would like to acknowledge Daniel Rodrigues, Ângela Ferreira, and Joana Pires for the support on experimental assays, NORTE-08-5369-FSE-000037 (H.R.M.); The Discoveries Centre for Regenerative and Precision Medicine (H2020-WIDESPREAD-2014-1-739572)