Vladimir Zachar

Aalborg University · Department of Health Science and Technology

In pre-clinical studies, human adipose-derived stem cells (hASCs) have shown great promise as a treatment modality for healing of cutaneous wounds. The advantages of hASCs are that they are relatively easy to obtain in large numbers from basic liposuctions, they maintain their characteristics after long-term in vitro culture, and they possess low i...

It has been suggested that immunophenotypically defined lineages within the in vitro expanded adipose-derived stem cell (ASC) may play a beneficial role from the perspective of a personalized intervention. Therefore, to better understand the implications of different surface marker profiles for the functionality, we set out to examine the evolution...

In order to enhance the therapeutic potential, it is important that sufficient knowledge regarding the dynamic changes of adipose-derived stem cell (ASC) immunophenotypical and biological properties during in vitro growth is available. Consequently, we embarked on a study to follow the evolution of highly defined cell subsets from three unrelated d...

Treatment of severe burn wounds presents a daunting medical challenge, and novel approaches promoting healing and reducing scarring are highly desirable. The application of mesenchymal stem/stromal cells (MSCs) has been suggested as a novel treatment. In this paper, we present systematic reviews of pre-clinical and clinical studies of MSC therapy f...

Purpose: To reveal the phenotypic differences between human ocular surface stromal cells (hOSSCs) cultured from the corneal, limbal, and scleral compartments. Methods: A comparative analysis of cultured hOSSCs derived from four unrelated donors was conducted by multichromatic flow cytometry for six distinct CD antigens, including the CD73, CD90,...

Adipose-derived stromal/stem cells (ASCs) are currently being considered for clinical use for a number of indications. In order to develop standardized clinical protocols, it is paramount to have a full characterization of the stem cell preparations. The surface marker expression of ASCs has previously been characterized in multiple studies. Howeve...

Chronic non-healing wounds are detrimental for the quality of life of the affected individuals and represent a major burden for the health care systems. Adipose-derived stem cells (ASCs) are being investigated for the development of novel treatments of chronic wounds, as they have shown several positive effects on wound healing. While these effects...

This study explored the feasibility of constructing a tissue engineered muscle layer in the oesophagus using oesophageal acellular matrix (OAM) scaffolds and human aortic smooth muscle cells (hASMCs) or human adipose-derived stem cells (hASCs). The second objective was to investigate the effect of hypoxic preconditioning of seeding cells on cell vi...

Ex‐vivo cultured human limbal epithelial stem/progenitor cells (hLESCs) are the main source for regenerative therapy of limbal stem cell deficiency (LSCD), which is worldwide one of the major causes of corneal blindness. Despite many stemness‐associated markers have been identified within the limbal niche, the phenotype of the earliest hLESCs has n...

Myogenic precursors sense and dynamically respond to mechanical stimulation through complex integrin-mediated mechanotransduction, in which focal adhesion kinase (FAK) is a fundamental intracellular signaling mediator. When skeletal myoblasts are exposed to uniaxial cyclic tensile strain (UCTS) they display uniform alignment and an enhanced rate of...

Smooth muscle differentiated adipose tissue-derived stem cells are a valuable resource for regeneration of gastrointestinal tissues, such as the gut and sphincters. Hypoxia has been shown to promote adipose tissue-derived stem cells proliferation and maintenance of pluripotency, but the influence of hypoxia on their smooth myogenic differentiation...

Background Transcriptomic profiling of ex vivo cultured human limbal epithelial stem cells (hLESCs) will foster better understanding of corneal physiology and novel treatment paradigms to limbal stem cell deficiency (LSCD). However, currently such profiling studies are hampered due to difficulties with producing sufficient amounts of intact mRNA fo...

Introduction: Chronic wounds remain as a significant burden for patients and healthcare system. An important component in the pathogenesis of non-healing wounds is dysfunction of macrophages. In normal-healing wounds, the classically activated pro-inflammatory " M1 " macrophages present at the early phases are replaced over time by alternatively ac...

Introduction: Ex vivo-expanded autologous myoblasts are being used in clinical trials for the treatment of various skeletal muscle conditions, including stress urinary incontinence caused by urethral sphincter damage. The use of fetal calf serum (FCS) as a growth media supplement in these procedures still raises various technical and ethical concer...

The synthesis and deposition of extracellular matrix (ECM) plays an important role in the healing of acute and chronic wounds. Consequently, the use of ECM as treatment for chronic wounds has been of special interest—both in terms of inducing ECM production by resident cells and applying ex vivo produced ECM. For these purposes, using adipose tissu...

Preclinical studies have suggested that paracrine factors from adipose-derived stem cells (ASCs) promote the healing of chronic wounds, and that the exposure of ASCs to hypoxia enhances their wound healing effect. To aid the translation of these findings into clinical use, robust wound models are necessary to explore each aspect of wound healing. T...

Skeletal muscle tissue engineering holds promise for the treatment of a variety of degenerative and traumatic muscle conditions. The ultimate goal of skeletal muscle tissue engineering is very challenging, since it needs to closely reproduce a highly complex structure consisting of muscle cells, connective tissue, blood vessels, and nerves. One of...

Background Complex immunophenotypic repertoires defining discrete adipose-derived stem cell (ASC) subpopulations may hold a key toward identifying predictors of clinical utility. To this end, we sorted out of the freshly established ASCs four subpopulations (SPs) according to a specific pattern of co-expression of six surface markers, the CD34, CD7...

Purpose: Adipose tissue derived stem cells (ASC) are being used for regeneration of smooth muscle containing tissue, such as blood vessels and sphincters. Hypoxia has been shown to promote ASC proliferation and maintenance of pluripotency, but the effect of hypoxia on differentiation and contraction of differentiated cells has not been studied. Thi...

Background Adipose-derived stem cells (ASCs) are being increasingly recognized for their potential to promote tissue regeneration and wound healing. These effects appear to be partly mediated by paracrine signaling pathways, and are enhanced during hypoxia. Mass spectrometry (MS) is a valuable tool for proteomic profiling of cultured ASCs, which ma...

Boron-doped nanocrystalline diamond (BNCD) films exhibit outstanding electrochemical properties that make them very attractive for the fabrication of electrodes for novel neural interfaces and prosthetics. In these devices, the physicochemical properties of the electrode materials are critical to ensure an efficient long-term performance. The aim o...

Boron-doped nanocrystalline diamond (BDD) electrodes have recently attracted attention as materials for neural electrodes due to their superior physical and electrochemical properties, however their biocompatibility remains largely unexplored. In this work, we aim to investigate the in vivo biocompatibility of BDD electrodes in relation to conventi...

Approach for histological sectioning. Macroscopic view of an implanted BDD electrode before tissue fixation seen from the ventral side. The histological sections were obtained perpendicularly across the electrode head, as indicated by the dotted line. The displayed histological section is oriented with the ventral side to the right.

Criteria used to evaluate the severity of the inflammatory response.

Criteria used to evaluate the degree of neovascularization.

Significance: In most clinical trials using adipose-derived stem cells (ASCs), the cells have been expanded in culture media supplemented with fetal calf serum. However, there is much interest in replacing fetal calf serum with human platelet lysate or using completely serum- and xenogeneic-free media. This study found that culture in fetal calf s...

Since the discovery of adipose-derived stem cells (ASCs), there have been high expectations of their putative clinical use. Recent advances support these expectations, and it is expected that the transition from pre-clinical and clinical studies to implementation as a standard treatment modality is imminent. However ASCs must be isolated and expand...

Although several mechanical cues are involved in the regulation of myogenic differentiation, the relevance of mechanical stimulation for muscle tissue engineering remains poorly understood. Here, we describe a novel methodology that allows imparting well-controlled mechanical stimulation patterns to cells cultured on flexible substrates, with the a...

A method by means of which one can synthesize unique platinum surfaces with controlled micro and nano-scale topographies through a combination of (GLAD) and colloidal surface patterning is presented. A great challenge when developing materials for application in biomedical engineering is to design interfaces that ultimately can control the interact...

Neural prostheses are devices that use electrical impulses to restore sensory or motor deficits following trauma or neurological diseases. In implanted devices, electrodes located in close proximity to the neural tissue are in charge of delivering the electrical impulses generated in a stimulation unit. The electrodes for neural stimulation possess...

Moderate hypoxic preconditioning of adipose-derived stem cells (ASCs) enhances properties such as proliferation and secretion of growth factors, representing a valuable strategy to increase the efficiency of cell-based therapies. In a wide variety of cells potassium (K+) channels are key elements involved in the cellular responses to hypoxia, sugge...

Although adult muscle tissue possesses an exceptional capacity for regeneration, in the case of large defects, the restoration to original state is not possible. A well-known source for the de novo regeneration are the adipose-derived stem cells (ASCs), which can be readily isolated and have been shown to have a broad differentiation and regenerati...

Purpose: Attempts to determine the transcriptional profile of discrete subsets of limbal epithelial cells in situ using laser capture microdissection (LCM) face two major challenges. First, the transcriptional profile of cells within a tissue may rapidly change as the tissue is excised and exposed to cold ischemia. Second, there is a risk of degrad...

Skeletal muscle tissue consists of a highly organized structure containing cells, connective tissue, blood vessels and innervation. Due to this complexity, engineering viable skeletal muscle still remains a major challenge. One of the first pre-requisites is to obtain cells arranged in parallel in order to efficiently produce force by contraction....

Nanocrystalline diamond (NCD) films have recently gained significant attention as biomaterials for a wide variety of applications, including orthopedic and neural devices. A chief advantage of NCD surfaces is their ability to support diverse functional groups, which would allow controlling the biological performance of implants. Since most cell typ...

Engineering skeletal muscle still remains a major challenge. Skeletal muscle comprises a highly organized structure containing cells arranged in parallel in order to contract as a syncytium. Previous work has shown that porous scaffolds with uncontrolled structure allow 3D growth of myoblasts. However, random structures are ineffective for proper d...

Human glioblastoma multiforme (GBM) is an aggressive cancer with a very poor prognosis. Cripto-1 (CR-1) has a key regulatory role in embryogenesis, while in adult tissue re-expression of CR-1 has been correlated to malignant progression in solid cancers of non-neuronal origin. As CR-1 expression has yet to be described in cerebral cancer and CR-1 i...

Corneal epithelium is maintained throughout life by well-orchestrated proliferation of limbal epithelial stem cells (LESCs), followed by migration and maturation centripetally towards the ocular surface. Disturbance of LESCs can potentially lead to a blinding condition, which can be reversed by reconstitution of a functional LESC pool. The current...

Human adipose-derived stromal cells (hASCs) possess the potential for chondrogenic differentiation. Recent studies imply that this differentiation process may be enhanced by culturing the cells in low oxygen tension in combination with three-dimensional (3D) scaffolds. We report the evaluation of the chondrogenic potential of hASC pellets in 5 and...

The adipose-derived stem cells (ASCs) possess potent immunomodulatory properties that could be exploited in developing novel regenerative medicine and tissue engineering therapies. As studies have shown, the immunomodulatory properties seem to be mediated by paracrine effects. However, the role of the different factors secreted by the cells in modu...

This study was conducted to perform global transcriptomic profiling and biomarker discovery on undisturbed human corneal epithelial subpopulations using a novel approach combining laser capture microdissection (LCM) and RNA sequencing. LCM facilitated the harvest of four cellular compartments along the corneal epithelial differentiation pathway: St...

Human glioblastoma multiforme (GBM) is an incurable form of cancer with a very poor prognosis. GBM characteristically grow by infiltrating the surrounding brain tissue and relapse is inevitable. Based on the hypothesis that a subpopulation of glioma initiating cells (GIS) are responsible for the regrowth of the tumour mass and relapse in GBM....

FABP7 expression in radial glial cells has been proposed to be the malignant glioma cell of origin and has been identified as one of the most distinct genes over expressed in glioblastoma multiform (GBM) cancer stem cells. It has been associated with regions of GBM tumour infiltration, relapse and reduced survival. Several regulatory elements a...

Gene ontology analysis of genes within the leading term Cell Development in BLCs. (A) Network of significantly enriched terms. (B) Bar chart of significantly enriched terms. Numbers next to the bars indicate total number of genes mapping to the specific term. (EPS)

The implementation of micro- and nanotechnologies to biomaterials constitutes a unique platform to improve our understanding on microenvironmental regulation of stem cell functions. In the recent years, various methods have been developed for the fabrication of micro- and nanopatterned polymeric culture substrates, and many of these novel surfaces...

Background: A modification of the Flexcell system that allows imposition of homogenous, controlled non-equibiaxial strains to cell cultures is developed and experimentally validated. The Flexcell system by default applies equibiaxial strain to cell cultures, meaning no shear strain, while soft tissue cells in vivo are subjected to a range of mecha...

The aim of this study was to determine whether the growth and differentiation of limbal epithelial stem cell cultures could be controlled through manipulation of the oxygen tension. Limbal epithelial cells were isolated from corneoscleral disks, and cultured using either feeder cells in a growth medium supplemented with serum (3T3 system) or withou...

Therapeutic advances do not circumvent the devastating fact that the survival rate in glioblastoma multiforme (GBM) is less than 5%. Nanoparticles consisting of liposome-based therapeutics are provided against a variety of cancer types including GBM, but available liposomal formulations are provided without targeting moieties, which increases the d...

Treatment of myocardial infarction (MI) with bone marrow-derived mesenchymal stem cells and recently also adipose-derived stem cells has shown promising results. In contrast to clinical trials and their use of autologous bone marrow-derived cells from the ischemic patient, the animal MI models are often using young donors and young, often immune-co...

Polydimethylsiloxane (PDMS) is the most common type of silicone polymer for the fabrication of implantable medical devices. Because of its inherent hydrophobic nature, the PDMS surface does not readily promote cellular adhesion, which leads to diverse clinical issues. Previously, we reported a simple water vapor plasma treatment of PDMS surfaces th...

Human multipotent mesenchymal stem cell (MSC) therapies are currently being tested in clinical trials for Crohn's disease, multiple sclerosis, graft-versus-host disease, type 1 diabetes, bone fractures, cartilage damage, and cardiac diseases. Despite remarkable progress in clinical trials, most applications still use traditional culture media conta...

Human adipose stem cells (hASCs) can promote angiogenesis through secretion of proangiogenic factors such as vascular endothelial growth factor (VEGF). In other cell types, it has been shown that induction of VEGF is mediated by both protease activated receptor 2 (PAR2) and hypoxia inducible factor 1(HIF-1). The present study hypothesized that PAR2...

Objectives: Ventricular constraint devices made of polyester and nitinol have been used to treat heart failure patients. Long-term follow-up has not demonstrated significant benefits, probably due to the lack of effects on myocardial tissue and to the risk of diastolic dysfunction. The goal of this experimental study is to improve ventricular cons...

Conventional culture surfaces do not provide optimal environmental cues for expansion or differentiation of adult stem cells. Aiming to increase the efficiency of the in vitro culture conditions, biocompatible and biodegradable biomaterials such as poly(lactic acid) (PLA) have been proposed to engineer the stem cell microenvironment. In this study,...

Development and implementation of therapeutic protocols based on stem cells or tissue-engineered products relies on methods that enable the production of substantial numbers of cells while complying with stringent quality and safety demands. In the current study, we aimed to assess the benefits of maintaining cultures of adipose-derived stem cells...

Human embryonic stem cells (hESCs) hold a great promise for regenerative medicine and tissue engineering. In order to obtain uniform hESC cultures without spontaneous differentiation, which is of interest for basic investigations as well as the development of future therapeutic protocols, it is important that specific culture conditions are adhered...

Ex vivo engineering of skeletal muscle represents an exciting new area of biotechnology. Although the ability of skeletal muscle cells to sense and respond to mechanical forces is well known, strategies based on the use of mechanical stimuli to optimize myogenesis in vitro remain limited. In this work, we describe a simple but powerful method based...