Bone Tissue Engineering in the Maxillofacial Region: The State-of-the-Art Practice and Future Prospects

Bone reconstruction in the maxillofacial region is a challenging task due to the exclusive anatomical complexity of the tissue, aesthetic requirements and functional demands. The gold standard method for maxillofacial reconstruction is based on autogenous bone grafting, which is associated with certain drawbacks. In this review, we describe recent bone tissue engineering approaches in reconstructive surgery of the maxillofacial region. Proper cell sources, scaffolds, signaling molecules as well as recent bioreactor technology are discussed.

Extracellular Matrix Disparities in an \u3ci\u3eNkx2-5\u3c/i\u3e Mutant Mouse Model of Congenital Heart Disease

Congenital heart disease (CHD) affects almost one percent of all live births. Despite diagnostic and surgical reparative advances, the causes and mechanisms of CHD are still primarily unknown. The extracellular matrix plays a large role in cell communication, function, and differentiation, and therefore likely plays a role in disease development and pathophysiology. Cell adhesion and gap junction proteins, such as integrins and connexins, are also essential to cellular communication and behavior, and could interact directly (integrins) or indirectly (connexins) with the extracellular matrix. In this work, we explore disparities in the expression and spatial patterning of extracellular matrix, adhesion, and gap junction proteins between wild type and Nkx2-5+/R52G mutant mice. Decellularization and proteomic analysis, Western blotting, histology, immunostaining, and mechanical assessment of embryonic and neonatal wild type and Nkx2-5 mutant mouse hearts were performed. An increased abundance of collagen IV, fibronectin, and integrin β-1 was found in Nkx2-5 mutant neonatal mouse hearts, as well as increased expression of connexin 43 in embryonic mutant hearts. Furthermore, a ventricular noncompaction phenotype was observed in both embryonic and neonatal mutant hearts, as well as spatial disorganization of ECM proteins collagen IV and laminin in mutant hearts. Characterizing such properties in a mutant mouse model provides valuable information that can be applied to better understanding the mechanisms of congenital heart disease

Nanocolumnar films: sustainable manufacturing and applications in biomedicine

Resumen del trabajo presentado en la 3rd International Conference on Nanomaterials Applied to Life Sciences (NALS 2022), celebrada en Santander (España), del 27 al 29 de abril de 2022Nanocolumnar films (NCFs) can be manufactured by glancing angle deposition with magnetron sputtering. This technique is environmentally friendly: it is carried out at RT in a single step (moderate energy consumption) and does not involve chemical products (no recycling issues). Depending on several parameters (namely the gas pressure, the electromagnetic power, the angle of inclination of the substrate and its possible rotation), the nanocolumnar structure can be controlled [1]. Moreover, this method can be scaled up to large surfaces, representing a valid approach for the industrial production of nanostructured films [2]. In particular, concerning biomedicine, NCFs made of Ti, Au and Pt have been fabricated and successfully employed in several applications. Ti NCFs can be used as antibacterial coatings for orthopedic implants [2,3]. Pt NCFs show improved properties as bioelectrodes for electric stimulation [4]. Finally, Au NCFs are excellent substrates for the identification of biomolecules in surface enhanced Raman spectroscopy, SERS [5]

Discrimination between the effects of pulsed electrical stimulation and electrochemically conditioned medium on human osteoblasts

Background Electrical stimulation is used for enhanced bone fracture healing. Electrochemical processes occur during the electrical stimulation at the electrodes and influence cellular reactions. Our approach aimed to distinguish between electrochemical and electric field effects on osteoblast-like MG-63 cells. We applied 20 Hz biphasic pulses via platinum electrodes for 2 h. The electrical stimulation of the cell culture medium and subsequent application to cells was compared to directly stimulated cells. The electric field distribution was predicted using a digital twin. Results Cyclic voltammetry and electrochemical impedance spectroscopy revealed partial electrolysis at the electrodes, which was confirmed by increased concentrations of hydrogen peroxide in the medium. While both direct stimulation and AC-conditioned medium decreased cell adhesion and spreading, only the direct stimulation enhanced the intracellular calcium ions and reactive oxygen species. Conclusion The electrochemical by-product hydrogen peroxide is not the main contributor to the cellular effects of electrical stimulation. However, undesired effects like decreased adhesion are mediated through electrochemical products in stimulated medium. Detailed characterisation and monitoring of the stimulation set up and electrochemical reactions are necessary to find safe electrical stimulation protocols.Open Access funding enabled and organized by Projekt DEAL. This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), grant number SFB ELAINE, 1270/1,2–299150580. We also acknowledge the funding from Atracción de Talento Programme, Modalidad‑1 Ref. 2019‑T1/IND‑1335 and the grant PID2021‑128611OB‑I00 funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe.Peer reviewe

Therapeutic Electrical Stimulation for Regenerative Medicine Application: A Need for a Credible In Vitro Model System

Trabajo presentado en la 30th Annual Conference of the European Society for Biomaterials (ESB-2019), celebrada en Dresden (Alemania), del 9 al 13 de septiembre de 2019Introduction Endogenous electric field (bioelectric field) is an electrical potential difference resulting from charge flow (current) in the body at all levels (i.e., cell, tissue, and organ), which is found to be essential in a variety of important biological process, such as healing and development 1 .Recent studies showed that manipulation of intrinsic bioelectric fields can cause disease or be used as therapeutics 2-4. Among the wide range of bioelectric fields, steady, long-lasting direct current (≈ 100 μA/cm2 ), also known as current of injury, generates a voltage gradient (≈ 10-100 mV/mm) between intact section and injured site that has regenerative effect and can change cell faith and responses. Experimental Methods We treated different cell types with low voltage electrical stimulation, within an invitro system, and induced different responses, such as differentiation, alignment, viability and proliferation (Figure 1). Results and Discussion These results suggest that electrical stimulation (ES), as a drug-free, cell-free approach, could be an attractive alternative for biochemical remedies and cell therapy approaches for tissue regeneration and wound healing. However, ES has not been widely accepted as a clinical treatment and it is only used as an adjunctive therapy. This is due to the lack of consistency in major outcomes, absence of coherency in defining ES protocols, and unmatchable results in vitro and in vivo. Moreover, there is inadequate understanding of the dominant mechanism of ES and leading parameters triggering the molecular cascades and generate the main changes in cellular level. Conclusion Here, I will discuss: 1) the current state-of-the-art on ES in vitro and in vivo and the common hypothesis on molecular mechanisms involved; 2) the confusions associated with protocols in vitro and in vivo and the incapability of the current devices to address remaining challenges; 3) the approaches intended to develop credible vitro models to provide a standard methodology for exploring ES to induce regeneration responses in tissues such as bone and nerves; 4) the future perspective including the incorporation of modern biomaterials (e.g., conductive nanomaterials, and polymers) and electronics.H2020-Marie Skłodowska Curie-Individual Fellowship currently supports this project (NeuPES ID:793102)

Bioelectric Potential in Next-Generation Organoids: Electrical Stimulation to Enhance 3D Structures of the Central Nervous System

Pluripotent stem cell-derived organoid models of the central nervous system represent one of the most exciting areas in in vitro tissue engineering. Classically, organoids of the brain, retina and spinal cord have been generated via recapitulation of in vivo developmental cues, including biochemical and biomechanical. However, a lesser studied cue, bioelectricity, has been shown to regulate central nervous system development and function. In particular, electrical stimulation of neural cells has generated some important phenotypes relating to development and differentiation. Emerging techniques in bioengineering and biomaterials utilise electrical stimulation using conductive polymers. However, state-of-the-art pluripotent stem cell technology has not yet merged with this exciting area of bioelectricity. Here, we discuss recent findings in the field of bioelectricity relating to the central nervous system, possible mechanisms, and how electrical stimulation may be utilised as a novel technique to engineer “next-generation” organoids.This work is supported by Luminesce Alliance (PPM1 K5116/RD274)—Innovation for Children’s Health for its contribution and support. Luminesce Alliance—Innovation for Children’s Health, is a not for profit cooperative joint venture between the Sydney Children’s Hospitals Network, the Children’s Medical Research Institute, and the Children’s Cancer Institute. It has been established with the support of the NSW Government to coordinate and integrate paediatric research. Luminesce Alliance is also affiliated with the University of Sydney and the University of New South Wales Sydney. Further support was provided by CSIC (ILINK+2020 Ref. LINKA20342) Programme from Spanish National Research Council (CSIC) and by the Australian Government Research Training Program (RTP) Scholarship

In vitro effect of direct current electrical stimulation on rat mesenchymal stem cells

Background: Electrical stimulation (ES) has been successfully used to treat bone defects clinically. Recently, both cellular and molecular approaches have demonstrated that ES can change cell behavior such as migration, proliferation and differentiation. Methods: In the present study we exposed rat bone marrow- (BM-) and adipose tissue- (AT-) derived mesenchymal stem cells (MSCs) to direct current electrical stimulation (DC ES) and assessed temporal changes in osteogenic differentiation. We applied 100 mV/mm of DC ES for 1 h per day for three, seven and 14 days to cells cultivated in osteogenic differentiation medium and assessed viability and calcium deposition at the different time points. In addition, expression of osteogenic genes, Runx2, Osteopontin, and Col1A2 was assessed in BM- and AT-derived MSCs at the different time points. Results: Results showed that ES changed osteogenic gene expression patterns in both BM- and AT-MSCs, and these changes differed between the two groups. In BM-MSCs, ES caused a significant increase in mRNA levels of Runx2, Osteopontin and Col1A2 at day 7, while in AT-MSCs, the increase in Runx2 and Osteopontin expression were observed after 14 days of ES. Discussion: This study shows that rat bone marrow- and adipose tissue-derived stem cells react differently to electrical stimuli, an observation that could be important for application of electrical stimulation in tissue engineering

Changes in the extracellular microenvironment and osteogenic responses of mesenchymal stem/stromal cells induced by in vitro direct electrical stimulation

Electrical stimulation (ES) has potential to be an effective tool for bone injury treatment in clinics. However, the therapeutic mechanism associated with ES is still being discussed. This study aims to investigate the initial mechanism of action by characterising the physical and chemical changes in the extracellular environment during ES and correlate them with the responses of mesenchymal stem/stromal cells (MSCs). Computational modelling was used to estimate the electrical potentials relative to the cathode and the current density across the cell monolayer. We showed expression of phosphorylated ERK1/2, c-FOS, c-JUN, and SPP1 mRNAs, as well as the increased metabolic activities of MSCs at different time points. Moreover, the average of 2.5 μM of HO and 34 μg/L of dissolved Pt were measured from the electrically stimulated media (ES media), which also corresponded with the increases in SPP1 mRNA expression and cell metabolic activities. The addition of sodium pyruvate to the ES media as an antioxidant did not alter the SPP1 mRNA expression, but eliminated an increase in cell metabolic activities induced by ES media treatment. These findings suggest that HO was influencing cell metabolic activity, whereas SPP1 mRNA expression was regulated by other faradic by-products. This study reveals how different electrical stimulation regime alters cellular regenerative responses and the roles of faradic by-products, that might be used as a physical tool to guide and control cell behaviour.BBSRC grant (BB/M013545/1). It also receives funding from The Royal Thai Government Scholarship (ST 4729) and Rosetrees Trust (M48