Current Tissue Engineering (Discontinued) - Volume 3, Issue 1, 2014

It is my great pleasure and honor to participate in the launching of the Volume 3, issue 01 of our journal “Current Tissue Engineering”. I would like to thank and pay tribute to the hard work and dedication of the editorial board members and staff. Without them this would not be possible. Tissue engineering is a rapidly growing interdisciplinary field involving the biological, chemical, physical, and engineering sciences. It uses a combination of cells and biomaterials to generate new functional tissues for implantation to repair or replace damaged tissues due to trauma, disease, or aging. In this issue, we have 3 review articles on the updated information of use of adipose tissue for tissue engineering: “ Recent advances and challenges in adipose tissue engineering: Adipose derived stem cell-based approaches: (Author: A. Cimpean): Autologous Fat Transfer and Cell-Based Strategies for Soft Tissue Reconstruction (Authors: Senarath-Yapa et al.) and “The future of neuroregenerative therapy for Parkinson’s disease” (Authors: Sugaya & Hendrix). We also have 1 review article on Biomaterial: “Potential of tissue engineered blood vessel as model to study effect of flow and wall thickness on cellular communication” (Authors: Ragaseema et al.). We have the first time 3 research articles: “Tubulin, F-box/leucine-rich repeat protein 14, and type 1 procollagen C-peptide in bovine periosteal cells β Association” (Author: M. Akiyama); Islet purification for clinical islet transplantation. (Author: H. Noguchi): “NMR-Relaxation and PFG NMR Studies of Water Dynamics in Oriented Collagen Fibres with different degree of cross-linking”. (Authors: Rodin and Nikerov). In future issues, it is my hope that we will expand our scope to include both review and full-length articles on biomechanics, mechano-biology and cellular therapies in both animal models and clinical trials.

The noncollagenous proteins UACA, EXOSC9, and TMX2 were previously identified in bovine periosteal cells with a combination of mass spectrometry and immunohistochemistry. In this study, the proteins β-tubulin, F-box/leucinerich repeat protein 14 (FBXL14), and type 1 procollagen C-peptide were investigated in these cells. Peptides of β-tubulin and FBXL14 were detected with liquid chromatography tandem mass spectrometry, with protein sequence coverages of 2% and 3%, respectively. A two-dimensional protein electrophoretic map of the culture supernatant of bovine periosteal cells suggested that TMX2 was close to type 1 procollagen C-peptide in the cell aggregate. Therefore, an immunohistochemical analysis of β-tubulin, FBXL14, and type 1 procollagen C-peptide was performed. The bovine periosteal cells were positive for β-tubulin, FBXL14, and type 1 procollagen C-peptide. The noncollagenous proteins β-tubulin and FBXL14 were thus identified, like UACA, EXOSC9, and TMX2, in bovine periosteal cells. Type 1 procollagen C-peptide was only expressed in a subset of cells, whereas type 1 collagen was expressed ubiquitously. It is possible that type 1 procollagen C-peptide is associated with those noncollagenous proteins. This study demonstrates the utility of a technique combining MS and immunohistochemistry.

Adipose tissue is now well recognized as a ubiquitously available and reliable source of multipotent adult stem cells. In the context of increasing clinical demand for adequate implants to repair soft tissue defects resulting from postoperative, congenital or posttraumatic loss of the subcutaneous fat layer, adipose tissue engineering (ATE) represents an exciting therapeutic strategy in plastic and reconstructive surgery. The ATE approach includes two different strategies: in situ adipogenesis for small volume loss, and in vitro development of three-dimensional (3D) tissue-engineered constructs (TECs) for large adipose tissue defects. These strategies can involve the use of living cells and/or biocompatible scaffolds and/or biomolecules. The focus of this review is on the use of adipose-derived stem cells (ASCs) as the cellular component of TECs for regenerative purposes. These cells have emerged as a promising type of stem cells with clear advantages over previously used mesenchymal stem cells, such as those derived from bone marrow (BM-MSCs) because of the easy and repeatable access to subcutaneous tissue, the simple isolation procedures, increased proliferation in culture and the potential to differentiate into cells of mesodermal origin as well as cells of non-mesodermal lineage. The culture strategies, immunophenotype, proliferation and differentiation potentials of ASCs, together with current clinical data with respect to their use in soft tissue regeneration and augmentation will be summarized. The article will also review the key advances in the development of biomaterial scaffolds and biomolecules aiming to control the cell response, as well as the possible challenges in this scientific field.

Parkinson's disease (PD), a prevalent geriatric neurodegenerative disorder, is characterized by selective dopaminergic neuronal death in the substantia nigra, leading to motor and non-motor symptoms. Current therapeutic options are limited to symptomatic relief that do not reverse the underlying pathology. Dopaminergic neural replacement through grafting of fetal mesencephalic tissue, while promising in theory, has had many barriers to routine clinical use. Such tissue survives and integrates poorly into recipients and has shown little benefit in sham-controlled surgical studies. Graftinduced dyskinesias often result from immune rejection and bias for serotonergic neuronal differentiation. Pluripotent embryonic stem cells (ES cells) are also theoretically promising but may form aberrant non-neural tissue and suffer graft rejection. Neural stem cell (NSCs) are a subset of adult stem cells that are limited to neural tissue differentiation and may be more easily expanded, integrated and regulated than fetal mesencephalic transplants or ES cells. Graft rejection and ethical issues would complicate use of allogeneic fetal NSCs, however. It would also be unsafe to obtain NSCs directly from patients given that they are present only within intricate brain regions and from adults have poor capacity for proliferation. Thus, the future of neuroregenerative therapy for PD may lie in generation of NSCs from patient-derived induced pluripotent stem cells (somatic cells artificially endowed with pluripotency) or endogenously increased by mitogenic drugs. Overall, therapy for Parkinson’s disease should be long-term and safe while producing expandable, integrated, and phenotypically balanced regeneration.

In clinical islet transplantation, islet purification reduces the amount of tissues to be transplanted by removing the acinar tissue, therefore minimizing the risks associated with intraportal infusion. On the other hand, the purification procedure may result in decreased numbers of islets recovered from digested tissue and may be traumatic for the islets. Ficoll- based density gradients are widely used in islet purification in clinical trials. Recently, purification with iodixanol was reported in an islet transplantation series with successful clinical outcomes. This review describes current advances in islet purification for clinical islet transplantation.

In physiology, blood vessel function is maintained mainly through nitric oxide (NO)-mediated cross-talk between endothelial cells (ECs) and smooth muscle cells (SMCs), which is compromised in pathology. Lack of an appropriate in vitro model hampers the study of vascular disease progression mechanisms. This study attempted to use tissue engineered blood vessel (TEBV) as a model system to understand the effect of wall thickness and shear stress on EC to SMC communication. Differentiated ECs and SMCs obtained by in vitro culture of sheep peripheral blood mononuclear cells (PBMNCs) were seeded on biodegradable €-polycaprolactone (PCL) conduits of different wall thicknesses and exposed to shear stress in a two-channel bioreactor to construct functional TEBV. Phenotypes of ECs and SMCs were studied in terms of nitric oxide synthase (eNOS) and basic calponin expressions respectively, using real time polymerase chain reaction. Endothelial to SMC cross-talk under the influence of wall thickness and shear stress was interrelated to NO and cyclic GMP (cGMP) production. Shear stress accelerates, but wall thickness has no influence on endothelial NO production. Increased release of NO in response to shear stress resulted in augmented cGMP production, but only when the wall thickness was lower. Both wall thickness and shear stress affect cGMP production and smooth muscle contractile phenotype. From this study, it is also suggested that TEBV may be a suitable model to study various risk factors on vessel integrity.

For collagen based tissue engineering it is important to know how the changes in water-biomolecules interactions are handled by the degree of cross-links in collagen nano-scaffolds. When hydration properties of collagens with different cross-linking are detailed by NMR a role of water interactions in improving collagen scaffold characteristics for tissue engineering could be clarified. A description of water diffusion in collagen fibres with cross-links should lead to better understanding of internal interactions and knowledge of porous media structure of collagen tissues. This paper presents the results of one- and two-dimensional NMR methods in studying molecular anisotropy and microstructure of collagen fibres from 2 connective tissues with different cross-linking levels (fibres from adult steer and young calf) at water content of 0.6 g water/g of dry matter. The NMR relaxation times (T1 and T2) have been studied in oriented collagen fibres (at 0° to the static magnetic field B0). The apparent translation diffusion coefficients (Dapp) at two directions of applied gradient – along the direction of static magnetic field B0 and perpendicular to B0 – have been studied in oriented collagen fibres (at 0° to the static magnetic field B0). The diffusion time dependence of Dapp showed for both directions of applied gradient a restriction for motion of water molecules. A model of equally spaced plane parallel permeable barriers developed by Tanner for NMR diffusion studies has been used for the estimation of restricted distance and permeability coefficient. Anisotropy of Dapp in oriented fibres was observed in both collagen tissues. Application of 2D DDCOSY NMR spectroscopy with two pairs of collinear gradients on collagen fibres oriented along the static magnetic field and simulations of diffusion anisotropy showed similar features on 2D diffusion maps.

Soft tissue deficits resulting from congenital deformities, aging, trauma, or post-surgical tissue loss are debilitating problems that can be challenging to reconstruct. However, the introduction of autologous fat transfer has revolutionized the field of soft tissue reconstruction and augmentation. Its abundance, ease of harvest, and immunocompatibility have made autologous fat an ideal candidate to correct contour deformities throughout the body. Nevertheless, there has been substantial inconsistency in reported outcomes due to variable rates of resorption. More recently, progress has been made in understanding the molecular mechanisms that govern adipogenesis and adipocyte survival. Furthermore, investigations continue on the large pool of resident adipose-derived stromal cells (ASCs) within fat, which may serve as a potential resource for tissue engineering. This review provides an overview on our current understanding of autologous fat grafting, adipose biology, adipose tissue engineering, and the potential role ASCs may play in modifying the local tissue environment to enhance fat transfer outcomes.