Purposes Of Regeneration Research Articles

Contribution of Physical Methods in Decellularization of Animal Tissues.

Biologic scaffolds composed of extracellular matrix (ECM) are frequently used for clinical purposes of tissue regeneration. Different methods have been developed for this purpose. All methods of decellularization including chemical and physical approaches leave some damage on the ECM; however, the effects of these methods are different which make some of these procedures more proper to maintain ECM structure than other methods. This review is aimed to introduce and compare new physical methods for the decellularization of different tissues and organs in tissue engineering. All recent reports and research that have used at least one physical method in the procedure of decellularization, were included and evaluated in this paper. The advantages and drawbacks of each method were examined and compared considering the effectiveness. This review tried to highlight the prospective potentials and benefits of applying physical methods for decellularization protocols in tissue engineering instead of the current chemical methods. These chemical methods are harsh in nature and were shown to be destructive and harmful to essential substances of ECM and scaffold structure. Therefore, using physical methods as a partial or even a whole protocol could save time, costs, and quality of the final acellular tissue in complicated decellularization procedures. Moreover, regarding the control factor that could be achieved easily with physical methods, optimization of different decellularization protocols would be quite satisfactory. Combined methods take advantage of both chemical and physical approaches.

The Intersection of Mechanotransduction and Regenerative Osteogenic Materials.

Mechanical signals play a central role in cell fate determination and differentiation in both physiologic and pathologic circumstances. Such signals may be delivered using materials to generate discrete microenvironments for the purposes of tissue regeneration and have garnered increasing attention in recent years. Unlike the addition of progenitor cells or growth factors, delivery of a microenvironment is particularly attractive in that it may reduce the known untoward consequences of the former two strategies, such as excessive proliferation and potential malignant transformation. Additionally, the ability to spatially modulate the fabrication of materials allows for the creation of multiple microenvironments, particularly attractive for regenerating complex tissues. While many regenerative materials have been developed and tested for augmentation of specific cellular responses, the intersection between cell biology and material interactions have been difficult to dissect due to the complexity of both physical and chemical interactions. Specifically, modulating materials to target individual signaling pathways is an avenue of interdisciplinary research that may lead to a more effective method of optimizing regenerative materials. In this work, the aim is to summarize the major mechanotransduction pathways for osteogenic differentiation and to consolidate the known materials and material properties that activate such pathways.

3D poly-ε-caprolactone/graphene porous scaffolds for bone tissue engineering

Three-dimensional biomedical scaffolds of porous biodegradable materials have been widely applied in tissue engineering for the purposes of bone repair and regeneration. In this study, porous biomedical scaffolds were fabricated by a solvent-casting/particulate-leaching method using poly-ε-caprolactone (PCL) as the matrix material, graphene platelets as the added material, and salt (NaCl) as the porogen material. First, the mechanical properties (compressive strength) and physical properties (porosity and contact angle) of the fabricated porous scaffolds were examined. Subsequently, weight loss and variations in pH values of the PCL/graphene scaffolds in a degradation test were determined. The biocompatibility of the fabricated PCL/graphene scaffolds was determined by seeding osteoblast-like (MG-63) cells in vitro. Graphene improved the mechanical properties of the 3D porous scaffold, and it changed the hydrophobic property of the surface of the 3D porous scaffold to a hydrophilic property. Cell attachment and proliferation improved with a higher ratio of graphene in the 3D porous scaffold (PCL/graphene).

In Vivo Assessment of a Hydroxyapatite/κ-Carrageenan-Maleic Anhydride-Casein/Doxorubicin Composite-Coated Titanium Bone Implant.

Here, we focus on the fabrications of an osteosarcoma implant for bone repair via the development of a hydroxyapatite/κ-carrageenan-maleic anhydride/casein with doxorubicin (HAP/κ-CA-MA-CAS/DOX) composite-deposited titanium (Ti) plate. The HAP/κ-CA-MA-CAS/DOX material was coated on the Ti plate through the EPD method (electrophoretic deposition), applying direct current (DC) signals to deposit the composite on the surface of the Ti plate. The physicochemical and morphological possessions and biocompatibility in vitro of the prepared nanocomposite were examined to assess its prospective effectiveness for purposes of bone regeneration. Excellent biocompatibility and elevated osteoconductivity were confirmed using MG63 osteoblast-like cells. In vivo studies were performed at tibia sites in Wistar rats, and rapid bone regeneration was detected at four weeks in defective bone. Overall, the studies demonstrate that the HAP/κ-CA-MA-CAS/DOX composite enhances the biocompatible and cell-stimulating biointerface of Ti metallic implants. As such, HAP/κ-CA-MA-CAS/DOX implants are viable prospects for osteosarcoma-affected bone regeneration.

Integrated urban regeneration based on an interdisciplinary experience in Lisbon (Regeneración urbana integrada basada en una experiencia interdisciplinar en Lisboa)

ABSTRACTEuropean policies recommend holistic approaches based on interdisciplinary teams when tackling the urban regeneration of residential buildings. This research presents the experience and findings of a collaborative research project between the disciplines of architecture and environmental psychology conducted in the Barrio das Estacas district of Lisbon, which has a significant elderly population. The experience combined a technical diagnosis of the public space and residential buildings together with a diagnosis of the psychosocial variables of its residents, obtained by means of surveys, enabling the development of effective action proposals that promote ‘ageing at home’. The research seeks to highlight the true value of characterizing the resident population and analysing their needs and demands for the purposes of urban regeneration through consultation processes, integrating the interdisciplinary perspective in the design of efficient intervention protocols for society. The results show that the residents are satisfied with their residential environment but have noted significant technical contraventions, requirements and demands for work that would improve their safety, health and comfort.

New Trends in Regenerative Medicine: Reprogramming and Reconditioning.

New Trends in Regenerative Medicine: Reprogramming and Reconditioning.

Urban Heat Island (UHI) risk maps as innovative tool for urban regeneration strategies. The case of Parma

For the purposes of regeneration of the consolidated city it is increasingly important to have the knowledge of the micro-scale distribution of the vulnerability of the population to the consequences of climate change and increasing urbanization. The work to be presented starts with the creation of maps of the risk classification induced by the heat islands in the city of Parma, and aims to investigate which are the most effective strategies that a Public Administration can adopt. The maps that have been created allow to assess the risk for the fragile population at the level of the single building. They relate the climatic datum of thermal variation with the population residing within each building, and verify the causal relationship with the soil sealing and with the morphology of the urban fabric. The results of the study can help to identify the thermal hot spot, receivers of specific mitigation actions. The risk map is itself a tool to develop multilevel actions, designed according to the peculiarities of the sites, where the possible adaptive solutions are compared with the physical and morphological characteristics of the places. The positive function of green infrastructures (contrast of overheating, flood mitigation, creation of places and services with a recreational function) is acquired by research and urban planning practice. It is equally well known the difficulty faced by Local Authorities in the maintenance and increase of unbuilt public areas, fundamental for the connection of ecological networks.

Наноматериалы и их роль в регенерации костной ткани

The paper reviews the literature on the morphology of bone tissue when using nanomaterials for the purposes of reparative regeneration. Non-biodegradable and biodegradable materials are characterized regarding their benefits and drawbacks in further practical application. Biodegradable nanomaterials reducing the risk of complications as well as bone repair time are currently studied and used in combination with donor cells, bioactive substances, or specialized nanoparticles for drug delivery and cell labeling. The trend is scheduled to replace the cast implant materials on the porous three-dimensional (3D) matrices. Pores of a certain size provide osteoconductivity of the material, which is mandatory for vascular growth and ingrowth of osteogenic cells inside the implant. Nanostructured materials contribute to the uniform distribution of osteoblasts around developing bone trabeculae thereby increasing the volume of restoring bone tissue. Keywords: nanomaterials, nanoparticles, bones, bone tissue, regeneration.

RGD-functionalized polyurethane scaffolds promote umbilical cord blood mesenchymal stem cell expansion and osteogenic differentiation.

Biomimetic materials are essential for the production of clinically relevant bone grafts for bone tissue engineering applications. Their ability to modulate stem cell proliferation and differentiation can be used to harness the regenerative potential of those cells and optimize the efficiency of engineered bone grafts. The arginyl-glycyl-aspartic acid (RGD) peptide has been recognized as the adhesion motif of various extracellular matrix proteins and can affect stem cell behaviour in biomaterials. Attempts to functionalize biomaterials with RGD have been limited to a maximum of 1- to 3-mm thickness scaffolds, overlooking the issue of core infiltration that represents a major hurdle in developing real thickness scaffolds. Herein, we present the cross-linking of RGD on the surface of "real thickness" (5×5×5mm) porous polyurethane scaffolds (PU-RGD), to be used for the expansion and osteogenic differentiation of umbilical cord blood mesenchymal stem cells (UCB MSCs). RGD-functionalized scaffolds increased initial cell adhesion (1.5-fold to twofold) and achieved a 3.4-fold increase in cell numbers at the end of culture compared with a 1.5-fold increase in non-functionalized controls. Homogenous cell infiltration to the scaffold core was observed in the PU-RGD scaffolds. Importantly, PU-RGD scaffolds were able to enhance the osteogenic differentiation of UCB MSCs. Osteogenic gene and protein expression increased in scaffolds functionalized with 100μg/ml RGD. Higher RGD concentrations (200μg/ml) were less efficient in stimulating osteogenic differentiation. We conclude that robust RGD tethering to 3D PU "real thickness" scaffolds is possible and that it promotes core infiltration, expansion, and osteogenic differentiation of UCB MSCs for the purposes of bone regeneration.

Ethno-nationally divided cities and the use of art for purposes of conflict resolution and urban regeneration

This paper examines ethno-nationally divided cities and how the arts are used in such contexts for conflict resolution and urban regeneration. Three ethno-nationally divided cities at different stages of conflict resolution – Jerusalem, Nicosia, Belfast – are juxtaposed and explored. Ethno-nationally divided cities, which have become defined by their separation, are increasingly being studied to understand a common urban experience, to consider how partition politics develop and to learn how to best avoid them. Parallel art practices are also noted in these three urban milieus, in so far as they aim to assist conflict resolution and create zones that facilitate social transformation. This article addresses the use of art as a tool of social cohesion, through examination of art projects targeted at ethno-national division and conflict. Looking at three different, but similar, cities demonstrates how art has been used at different stages of the desegregation process, and how these processes can potentially lead to new patterns of divisions. The use of the arts in divided city contexts is related to art used in broader urban contexts to address segregation and facilitate social engagement and shared spaces.

Scaffolds and cells for tissue regeneration: different scaffold pore sizes-different cell effects.

During the last decade biomaterial sciences and tissue engineering have become new scientific fields supplying rising demand of regenerative therapy. Tissue engineering requires consolidation of a broad knowledge of cell biology and modern biotechnology investigating biocompatibility of materials and their application for the reconstruction of damaged organs and tissues. Stem cell-based tissue regeneration started from the direct cell transplantation into damaged tissues or blood vessels. However, it is difficult to track transplanted cells and keep them in one particular place of diseased organ. Recently, new technologies such as cultivation of stem cell on the scaffolds and subsequently their implantation into injured tissue have been extensively developed. Successful tissue regeneration requires scaffolds with particular mechanical stability or biodegradability, appropriate size, surface roughness and porosity to provide a suitable microenvironment for the sufficient cell-cell interaction, cell migration, proliferation and differentiation. Further functioning of implanted cells highly depends on the scaffold pore sizes that play an essential role in nutrient and oxygen diffusion and waste removal. In addition, pore sizes strongly influence cell adhesion, cell-cell interaction and cell transmigration across the membrane depending on the various purposes of tissue regeneration. Therefore, this review will highlight contemporary tendencies in application of non-degradable scaffolds and stem cells in regenerative medicine with a particular focus on the pore sizes significantly affecting final recover of diseased organs.

Ultrasound-mediated gene transfer (sonoporation) in fibrin-based matrices: potential for use in tissue regeneration

It has been suggested that gene transfer into donor cells is an efficient and practical means of locally supplying requisite growth factors for applications in tissue regeneration. Here we describe, for the first time, an ultrasound-mediated system that can non-invasively facilitate gene transfer into cells entrapped within fibrin-based matrices. Since ultrasound-mediated gene transfer is enhanced using microbubbles, we compared the efficacy of neutral and cationic forms of these reagents on the ultrasound-stimulated gene transfer process in gel matrices. In doing so we demonstrated the beneficial effects associated with the use of cationic microbubble preparations that interact directly with cells and nucleic acid within matrices. In some cases, gene expression was increased two-fold in gel matrices when cationic microbubbles were compared with neutral microbubbles. In addition, incorporating collagen into fibrin gels yielded a 25-fold increase in gene expression after application of ultrasound to microbubble-containing matrices. We suggest that this novel system may facilitate non-invasive temporal and spatial control of gene transfer in gel-based matrices for the purposes of tissue regeneration.

Continuous sorption of synthetic dyes on dried biomass of microalga Chlorella pyrenoidosa

AbstractThe sorption of thioflavine T (TT) and malachite green (MG) cationic synthetic dyes on dried biomass of green microalga (Chlorella pyrenoidosa) immobilised in polyurethane foam under continuous column systems conditions using spectrophotometric methods of detection was investigated. Data characterising the sorption of TT and MG on microalgal biomass immobilised in polyurethane foam in a column system from single (C 0 = 25 μmol dm−3) or binary equimolar (C 0 = 25 μmol dm−3) dye solutions in the form of breakthrough curves were well described by the Thomas (R 2 = 0.994–0.912), Yoon-Nelson (R 2 = 0.994–0.911), and Clark (R 2 = 0.993–0.911) models. Useful parameters characterising the sorption column system were obtained from these mathematical models. The Thomas model, in particular, provided the Q max (maximal sorption capacity in μmol g−1) parameter for characterisation of biosorbent and also for evaluation of competitive effects in the TT and MG dyes sorption. For the purposes of biomass regeneration, a one-step desorption of the dyes studied from the microalgal biomass in batch and continuous column systems was performed. Efficiency of TT desorption from microalgal biomass increased in the order: deionised H2O (50.7 %), 99.5 vol. % 1,4-dioxane (67 %), 20 mmol dm−3 NiCl2 (83 %), 96 vol. % ethanol (85 %), 0.1 mol dm−3 HCl (89 %), 1 mol dm−3 acetic acid (89 %). In the case of MG, the desorption efficiency increased in the order: deionised H2O (13 %), 20 mmol dm−3 NiCl2 (50 %), 0.1 mol dm−3 HCl (91 %), 99.5 vol. % 1,4-dioxane (94 %), 1 mol dm−3 acetic acid (99 %), 96 vol. % ethanol (> 99 %). The presence of carboxyl, phosphoryl, amino, and hydroxyl groups, the important functional groups for sorption of cationic xenobiotics, was also confirmed on the algae biomass surface by potentiometric titration and ProtoFit modelling software. The data obtained showed that the dried immobilised algae biomass could be used as a sorbent for removing toxic xenobiotics from liquid wastewaters or contaminated waters and also presenting the possibilities of mathematical modelling of sorption processes in continuous column systems in order to obtain important parameters for use in practice.

Impaired neurovascular repair in subjects with diabetes following experimental intracutaneous axotomy

Diabetic complications and vascular disease are closely intertwined. Diabetes mellitus is a well-established risk factor for both large and small vessel vascular changes, and conversely other vascular risk factors confer increased risk for diabetic complications such as peripheral neuropathy, nephropathy and retinopathy. Furthermore, axons and blood vessels share molecular signals for purposes of navigation, regeneration and terminal arborizations. We examined blood vessel, Schwann cell and axonal regeneration using validated axotomy models to study and compare patterns and the relationship of regeneration among these different structures. Ten subjects with diabetes mellitus complicated by neuropathy and 10 healthy controls underwent 3 mm distal thigh punch skin biopsies to create an intracutaneous excision axotomy followed by a concentric 4-mm overlapping biopsy at different time points. Serial sections were immunostained against a pan-axonal marker (PGP9.5), an axonal regenerative marker (GAP43), Schwann cells (p75) and blood vessels (CD31) to visualize regenerating structures in the dermis and epidermis. The regenerative and collateral axonal sprouting rates, blood vessel growth rate and Schwann cell density were quantified using established stereology techniques. Subjects also underwent a chemical 'axotomy' through the topical application of capsaicin, and regenerative sprouting was assessed by the return of intraepidermal nerve fibre density through regenerative regrowth. In the healed 3 mm biopsy sites, collateral and dermal regenerative axonal sprouts grew into the central denervated area in a stereotypic pattern with collateral sprouts growing along the dermal-epidermal junction while regenerative dermal axons, blood vessels and Schwann cells grew from their transected proximal stumps into the deep dermis. Vessel growth preceded axon and Schwann cell migration into the denervated region, perhaps acting as scaffolding for axon and Schwann cell growth. In control subjects, Schwann cell growth was more robust and extended into the superficial dermis, while among subjects with diabetes mellitus, Schwann tubes appeared atrophic and were limited to the mid-dermis. Rates of collateral (P=0.0001), dermal axonal regenerative sprouting (P=0.02), Schwann cell migration (P<0.05) and blood vessel growth (P=0.002) were slower among subjects with diabetes mellitus compared with control subjects. Regenerative deficits are a common theme in diabetes mellitus and may underlie the development of neuropathy. We observed that blood vessel growth recapitulated the pattern seen in ontogeny and preceded regenerating nerve fibres, suggesting that enhancement of blood vessel growth might facilitate axonal regeneration. These models are useful tools for the efficient investigation of neurotrophic and regenerative drugs, and also to explore factors that may differentially affect axonal regeneration.

Memory Encoded Throughout Our Bodies: Molecular and Cellular Basis of Tissue Regeneration

When a sheep loses its tail, it cannot regenerate it in the manner of lizards. On the other hand, it is possible to clone mammals from somatic cells, showing that a complete developmental program is intact in a wounded sheep's tail the same way it is in a lizard. Thus, there is a requirement for more than only the presence of the entire genetic code in somatic cells for regenerative abilities. Thoughts like this have motivated us to assemble more than just a factographic synopsis on tissue regeneration. As a model, we review skin wound healing in chronological order, and when possible, we use that overview as a framework to point out possible mechanisms of how damaged tissues can restore their original structure. This article postulates the existence of tissue structural memory as a complex distributed homeostatic mechanism. We support such an idea by referring to an extremely fragmented literature base, trying to synthesize a broad picture of important principles of how tissues and organs may store information about their own structure for the purposes of regeneration. Selected developmental, surgical, and tissue engineering aspects are presented and discussed in the light of recent findings in the field. When a sheep loses its tail, it cannot regenerate it in the manner of lizards. On the other hand, it is possible to clone mammals from somatic cells, showing that a complete developmental program is intact in a wounded sheep's tail the same way it is in a lizard. Thus, there is a requirement for more than only the presence of the entire genetic code in somatic cells for regenerative abilities. Thoughts like this have motivated us to assemble more than just a factographic synopsis on tissue regeneration. As a model, we review skin wound healing in chronological order, and when possible, we use that overview as a framework to point out possible mechanisms of how damaged tissues can restore their original structure. This article postulates the existence of tissue structural memory as a complex distributed homeostatic mechanism. We support such an idea by referring to an extremely fragmented literature base, trying to synthesize a broad picture of important principles of how tissues and organs may store information about their own structure for the purposes of regeneration. Selected developmental, surgical, and tissue engineering aspects are presented and discussed in the light of recent findings in the field.

THE PREVENTION OF HYPOCHROMIC ANEMIA IN PREGNANCY

Within the past decade the high incidence of anemia in pregnancy has become generally appreciated. Although the work of Strauss and Castle,¹Dieckmann and Wegner²and others has indicated that a 10 to 20 per cent lowering of the hemoglobin during pregnancy may be the result of hydremia and not represent true anemia, approximately 25 per cent of otherwise normal women are definitely anemic following parturition.³The vast majority of such patients have anemia of the hypochromic variety,⁴which has come to be associated with a virtual deficiency of available iron for purposes of blood regeneration within the body. Strauss and Castle,⁵Davies and Shelley⁶and other clinicians have shown that in pregnancy this anemia is to be associated not only with the presence of the fetus but also with gastric secretory defects and inadequate diets and usually may be completely relieved equally well