ATMP-classified, scalable, autologous cell spray for the treatment of skin wounds and assessment of its effects on wound healing clinically and on a molecular level.

BACKGROUND: Autologous split-thickness skin grafts (STSGs) are the standard of care for closure of deep and large burns. However, perforation and extensive fishnet-like expansion of the grafts to achieve greater area wound coverage can lead to treatment failures or esthetically poor healing outcomes and scarring. The purpose of this study was to validate an autologous advanced therapy medicinal product (ATMP)-compliant skin cell suspension and evaluate its efficacy to promote epithelialization. METHODS: Cells isolated from a piece of STSG according to ATMP classification requirements were sprayed onto 20 patients during a single operation in a validation study. Comparative evaluation of treatment efficacy was carried out using side-by-side skin graft donor site wounds that were standardized in depth. Firstly, we characterized wound healing transcriptomes at 14 and 21 days from serial wound biopsies in seven patients. Then, side-by-side wounds in four patients were treated with or without the skin cells. The wounds were photographed, clinical outcomes assessed, and the treatment and control wound transcriptomes at 14 days were compared to the untreated wounds' healing transcriptomes. RESULTS: The average cell yield after isolation from the STSG was 2.4 × 106 cells/cm2 with 96 % viability. The product contained mainly keratinocytes and their precursors but also other skin cells such as fibroblasts were present. As compared to vehicle-treated donor site wounds, the wounds treated with cells demonstrated improved epithelialization by both direct comparison and machine learning analysis of the transcriptomes. CONCLUSIONS: We showed that rapid and scalable ATMP-classified processing of skin cells is feasible, and application of the skin cells effectively promotes healing and epithelization of donor site wounds.

Discovery of Small Molecules that Activate RNA Methylation through Cooperative Binding to the METTL3-14-WTAP Complex Active Site.

Chemical modifications of RNA provide an additional, epitranscriptomic, level of control over cellular functions. N-6-methylated adenosines (m6As) are found in several types of RNA, and their amounts are regulated by methyltransferases and demethylases. One of the most important enzymes catalyzing generation of m6A on mRNA is the trimer N-6-methyltransferase METTL3-14-WTAP complex. Its activity has been linked to such critical biological processes as cell differentiation, proliferation, and death. We used in silico-based discovery to identify small-molecule ligands that bind to METTL3-14-WTAP and determined experimentally their binding affinity and kinetics, as well as their effect on enzymatic function. We show that these ligands serve as activators of the METTL3-14-WTAP complex.

VEGF-B gene therapy inhibits doxorubicin-induced cardiotoxicity by endothelial protection.

Congestive heart failure is one of the leading causes of disability in long-term survivors of cancer. The anthracycline antibiotic doxorubicin (DOX) is used to treat a variety of cancers, but its utility is limited by its cumulative cardiotoxicity. As advances in cancer treatment have decreased cancer mortality, DOX-induced cardiomyopathy has become an increasing problem. However, the current means to alleviate the cardiotoxicity of DOX are limited. We considered that vascular endothelial growth factor-B (VEGF-B), which promotes coronary arteriogenesis, physiological cardiac hypertrophy, and ischemia resistance, could be an interesting candidate for prevention of DOX-induced cardiotoxicity and congestive heart failure. To study this, we administered an adeno-associated viral vector expressing VEGF-B or control vector to normal and tumor-bearing mice 1 wk before DOX treatment, using doses mimicking the concentrations used in the clinics. VEGF-B treatment completely inhibited the DOX-induced cardiac atrophy and whole-body wasting. VEGF-B also prevented capillary rarefaction in the heart and improved endothelial function in DOX-treated mice. VEGF-B also protected cultured endothelial cells from apoptosis and restored their tube formation. VEGF-B increased left ventricular volume without compromising cardiac function, reduced the expression of genes associated with pathological remodeling, and improved cardiac mitochondrial respiration. Importantly, VEGF-B did not affect serum or tissue concentrations of DOX or augment tumor growth. By inhibiting DOX-induced endothelial damage, VEGF-B could provide a novel therapeutic possibility for the prevention of chemotherapy-associated cardiotoxicity in cancer patients.

The Paracrine Effect of Skeletal Myoblasts Is Cardioprotective Against Oxidative Stress and Involves EGFR-ErbB4 Signaling, Cystathionase, and the Unfolded Protein Response.

Therapeutic effects of skeletal myoblast transplantation into the myocardium are mediated via paracrine factors. We investigated the ability of myoblast-derived soluble mediators to protect cardiomyocytes from oxidative stress. Fetal rat cardiac cells were treated with conditioned medium from cultures of myoblasts or cardiac fibroblasts, and oxidative stress was induced with H2O2. Myoblast-derived factors effectively prevented oxidative stress-induced cardiac cell death and loss of mitochondrial membrane potential. This protective effect was mediated via epidermal growth factor (EGF) receptor and c-Met signaling, and mimicked by neuregulin 1 but not EGF. Microarray analysis of cardiac cells treated with myoblast versus cardiac fibroblast-derived mediators revealed differential regulation of genes associated with antioxidative effects: cystathionine-γ-lyase (cst), xanthine oxidase, and thioredoxin-interacting protein as well as tribbles homolog 3 (trib3). Cardiac cell pretreatment with tunicamycin, an inducer of trib3, also protected them against H2O2-induced cell death. Epicardial transplantation of myoblast sheets in a rat model of acute myocardial infarction was used to evaluate the expression of CST and trib3 as markers of myoblasts' paracrine effect in vivo. Myoblast sheets induced expression of the CST as well as trib3 in infarcted myocardium. CST localized around blood vessels, suggesting smooth muscle cell localization. Our results provide a deeper molecular insight into the therapeutic mechanisms of myoblast-derived paracrine signaling in cardiac cells and suggest that myoblast transplantation therapy may prevent oxidative stress-induced cardiac deterioration and progression of heart failure.

Mitochondrial respiratory dysfunction due to the conversion of substituted cathinones to methylbenzamides in SH-SY5Y cells.

The increased use of cathinone-type designer drugs, known as legal highs, has led to concerns about their potential neurotoxicity due to their similarity to methamphetamine (METH). Therefore, closer investigations of their toxic effects are needed. We investigated the effects of the cathinones 4-methylmethcathinone (4-MMC) and 3,4-methylenedioxymethcathinone (MDMC) and the amphetamine METH on cytotoxicity and mitochondrial respiration in SH-SY5Y neuroblastoma cells. We also investigated the contribution of reactive species, dopamine, Bcl-2 and tumor necrosis factor α (TNFα) on toxicity. Finally, we investigated the effect of cathinone breakdown products using ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry and studied their involvement in toxicity. We observed dose-dependent increases in cytotoxicity and decreases in mitochondrial respiration following treatment with all cathinones and amphetamines. Glutathione depletion increases amphetamine, but not cathinone toxicity. Bcl-2 and TNFα pathways are involved in toxicity but dopamine levels are not. We also show that cathinones, but not amphetamines, spontaneously produce reactive species and cytotoxic methylbenzamide breakdown products when in aqueous solution. These results provide an important first insight into the mechanisms of cathinone cytotoxicity and pave the way for further studies on cathinone toxicity in vivo.

Comparison of arrhythmogenicity and proinflammatory activity induced by intramyocardial or epicardial myoblast sheet delivery in a rat model of ischemic heart failure.

Although cell therapy of the failing heart by intramyocardial injections of myoblasts to results in regenerative benefit, it has also been associated with undesired and prospectively fatal arrhythmias. We hypothesized that intramyocardial injections of myoblasts could enhance inflammatory reactivity and facilitate electrical cardiac abnormalities that can be reduced by epicardial myoblast sheet delivery. In a rat model of ischemic heart failure, myoblast therapy either by intramyocardial injections or epicardial cell sheets was given 2 weeks after occlusion of the coronary artery. Ventricular premature contractions (VPCs) were assessed, using an implanted three-lead electrocardiograph at 1, 7, and 14 days after therapy, and 16-point epicardial electropotential mapping (EEPM) was used to evaluate ventricular arrhythmogenicity under isoproterenol stress. Cardiac functioning was assessed by echocardiography. Both transplantation groups showed therapeutic benefit over sham therapy. However, VPCs were more frequent in the Injection group on day 1 and day 14 after therapy than in animals receiving epicardial or sham therapy (p < 0.05 and p < 0.01, respectively). EEPM under isoproterenol stress showed macroreentry at the infarct border area, leading to ventricular tachycardias in the Injection group, but not in the myoblast sheet- or sham-treated groups (p = 0.045). Both transplantation types modified the myocardial cytokine expression profile. In animals receiving epicardial myoblast therapy, selective reductions in the expressions of interferon gamma, interleukin (IL)-1ß and IL12 were observed, accompanied by reduced infiltration of inflammatory CD11b- and CD68-positive leukocytes, compared with animals receiving myoblasts as intramyocardial injections. Intramyocardial myoblast delivery was associated with enhanced inflammatory and immunomodulatory reactivity and increased frequency of VPCs. In comparison to intramyocardial injection, the epicardial route may serve as the preferred method of skeletal myoblast transplantation to treat heart failure.

Recombinant human collagen III gel for transplantation of autologous skin cells in porcine full-thickness wounds.

Complex skin wounds, such as chronic ulcers and deep burns, require lengthy treatments and cause extensive burdens on healthcare and the economy. Use of biomaterials and cell transplantation may improve traditional treatments and promote the healing of difficult-to-treat wounds. In this study, we investigated the use of recombinant human collagen III (rhCol-III) gel as a delivery vehicle for cultured autologous skin cells (keratinocytes only or keratinocyte-fibroblast mixtures). We examined its effect on the healing of full-thickness wounds in a porcine wound-healing model. Two Landrace pigs were used for the study. Fourteen deep dermal wounds were created on the back of each pig with an 8 mm biopsy punch. Syringes containing acellular rhCol-III gel (n = 8) or rhCol-III gel with autologous keratinocytes (n = 8) or rhCol-III gel with autologous keratinocytes and fibroblasts (n = 8) were applied into wounds. Untreated wounds were used as controls for the treatment groups (n = 4). We used rhCol-III gel to manufacture a cell-delivery syringe containing autologous skin cells. In a full-thickness wound-healing model, we observed that rhCol-III gel enhances early granulation tissue formation. Interestingly, we found cell type-dependent differences in the stability of rhCol-III in vivo. Fibroblast-containing gel was effectively removed from the wound, whereas gels without cells or with keratinocytes only remained intact. Our results demonstrate that the properties of rhCol-III gel for skin cell transplantation can be significantly altered in a cell type-dependent manner.

Gene expression profiling of negative-pressure-treated skin graft donor site wounds.

Negative-pressure wound therapy (NPWT) is widely used to improve skin wound healing. Although NPWT has been studied as a treatment for wound closure and healing, the molecular mechanisms explaining its therapeutic effects remain unclear. To investigate the effect of NPWT on gene expression, and to discover the genes most dominantly responding to this treatment during skin wound healing, we applied negative pressure on split-thickness skin graft donor sites from the first postoperative day (POD) to the seventh POD. Biopsies were collected from 4 NPWT-treated and 2 control patients. Two biopsy samples were taken from each patient: one from intact skin before graft harvesting, and one on the seventh POD from the donor site wound. Genome-wide microarrays were performed on all samples. Gene expression changes on the seventh POD were compared between NPWT and control patients, and were analyzed for statistical significance. In addition, we analyzed wound exudates for volume, and for concentrations of leukocytes, erythrocytes, and haemoglobin. NPWT induced major changes in gene expression during healing. These changes ranged from 10-fold induction to 27-fold suppression. The genes most induced were associated with cell proliferation and inflammation, and the most down-regulated genes were linked to epidermal differentiation. Our results provide the first insight into the molecular mechanisms behind NPWT, and suggest that NPWT enhances specific inflammatory gene expression at the acute phase associated with epithelial migration and wound healing. However, its continued use may inhibit epithelial differentiation.

Human skin transcriptome during superficial cutaneous wound healing.

Healing of the epidermis is a crucial process for maintaining the skin's defense integrity and its resistance to environmental threats. Compromised wound healing renders the individual readily vulnerable to infections and loss of body homeostasis. To clarify the human response of reepithelialization, we biopsied split-thickness skin graft donor site wounds immediately before and after harvesting, as well as during the healing process 3 and 7 days thereafter. In all, 25 biopsies from eight patients qualified for the study. All samples were analyzed by genome-wide microarrays. Here, we identified the genes associated with normal skin reepithelialization over time and organized them by similarities according to their induction or suppression patterns during wound healing. Our results provide the first elaborate insight into the transcriptome during normal human epidermal wound healing. The data not only reveal novel genes associated with epidermal wound healing but also provide a fundamental basis for the translational interpretation of data acquired from experimental models.

Advances in cell transplantation therapy for diseased myocardium.

The overall objective of cell transplantation is to repopulate postinfarction scar with contractile cells, thus improving systolic function, and to prevent or to regress the remodeling process. Direct implantation of isolated myoblasts, cardiomyocytes, and bone-marrow-derived cells has shown prospect for improved cardiac performance in several animal models and patients suffering from heart failure. However, direct implantation of cultured cells can lead to major cell loss by leakage and cell death, inappropriate integration and proliferation, and cardiac arrhythmia. To resolve these problems an approach using 3-dimensional tissue-engineered cell constructs has been investigated. Cell engineering technology has enabled scaffold-free sheet development including generation of communication between cell graft and host tissue, creation of organized microvascular network, and relatively long-term survival after in vivo transplantation.

hHGF overexpression in myoblast sheets enhances their angiogenic potential in rat chronic heart failure.

After severe myocardial infarction (MI), heart failure results from ischemia, fibrosis, and remodeling. A promising therapy to enhance cardiac function and induce therapeutic angiogenesis via a paracrine mechanism in MI is myoblast sheet transplantation. We hypothesized that in a rat model of MI-induced chronic heart failure, this therapy could be further improved by overexpression of the antiapoptotic, antifibrotic, and proangiogenic hepatocyte growth factor (HGF) in the myoblast sheets. We studied the ability of wild type (L6-WT) and human HGF-expressing (L6-HGF) L6 myoblast sheet-derived paracrine factors to stimulate cardiomyocyte, endothelial cell, or smooth muscle cell migration in culture. Further, we studied the autocrine effect of hHGF-expression on myoblast gene expression profiles by use of microarray analysis. We induced MI in Wistar rats by left anterior descending coronary artery (LAD) ligation and allowed heart failure to develop for 4 weeks. Thereafter, we administered L6-WT (n = 15) or L6-HGF (n = 16) myoblast sheet therapy. Control rats (n = 13) underwent LAD ligation and rethoracotomy without therapy, and five rats underwent a sham operation in both surgeries. We evaluated cardiac function with echocardiography at 2 and 4 weeks after therapy, and analyzed cardiac angiogenesis and left ventricular architecture from histological sections at 4 weeks. Paracrine mediators from L6-HGF myoblast sheets effectively induced migration of cardiac endothelial and smooth muscle cells but not cardiomyocytes. Microarray data revealed that hHGF-expression modulated myoblast gene expression. In vivo, L6-HGF sheet therapy effectively stimulated angiogenesis in the infarcted and non-infarcted areas. Both L6-WT and L6-HGF therapies enhanced cardiac function and inhibited remodeling in a similar fashion. In conclusion, L6-HGF therapy effectively induced angiogenesis in the chronically failing heart. Cardiac function, however, was not further enhanced by hHGF expression.

Bcl-2 improves myoblast sheet therapy in rat chronic heart failure.

Myoblast transplantation therapy for chronic heart failure (HF) is impaired by early donor cell death and reduced graft viability. Although epicardial implantation of cell sheets can prevent the initial loss of transplanted cells, limited vascularization subjects the sheets to apoptotic stress. We studied the efficacy of antiapoptotic bcl2 in myoblast sheet therapy for rat chronic HF. Myocardial infarction was induced by left anterior descending coronary artery ligation and HF was allowed to develop for 4 weeks. Thereafter, wild type (L6-WT; n=16) or Bcl-2-expressing (L6-Bcl2; n=19) myoblast sheets were transplanted epicardially. Control rats (n=21) underwent left anterior descending coronary artery ligation and re-thoracotomy. Five rats were sham-operated in both surgeries. Four weeks after transplantation, only the L6-Bcl2 rats showed improved left ventricular ejection fraction. Their vascular density in the damaged myocardium was greater, and they had more proliferating cells. The L6-Bcl2 group had an increased amount of myocytes in the infarct area. Soluble factors from L6-Bcl2 sheets induced a 2.9-fold increase in endothelial cell proliferation, and enhanced endothelial wound healing as compared to the L6-WT sheets. These effects were inhibited by SU5416 and were thus dependent on Flt1/Flk1 signaling. In conclusion, bcl2 improves efficacy of myoblast sheet transplantation and promotes proangiogenic paracrine signaling.

Paracrine factors from fibroblast aggregates in a fibrin-matrix carrier enhance keratinocyte viability and migration.

Efficient re-epithelialization of skin lesions is dependent on paracrine support from connective tissue fibroblasts. In deep skin defects, the supporting growth factor incentive is lacking. Current methods of keratinocyte transplantation with compromised attachment, spread, and cell proliferation warrant improvement and refinement. We describe here how human keratinocytes can be stimulated by matrix-embedded factors from a novel process of fibroblast activation: nemosis. Interestingly, the unique set of mediators released in this process also plays a key role in normal wound healing. To develop a system for targeted delivery of nemosis-derived paracrine effectors, herein designated as Finectra, we combined them with fibrin to establish a controlled-release gel. Keratinocytes seeded to cover this active matrix showed better adherence, outgrowth, and viability than did cells on control matrix. The matrix incorporating Finectra supported viability of both primary keratinocytes and green fluorescent protein (GFP)-labeled HaCaT cells, as evaluated by MTT assay and persistence of GFP-fluorescence. The fibrin-Finectra matrix promoted migration of keratinocytes to cover a larger area on the matrix, suggesting better wound coverage on transplantation. An inhibitor of EGFR/c-Met receptor tyrosine kinases abolished keratinocyte responses to fibrin-Finectra matrix. This matrix can thus deliver biologically relevant synergistic stimuli to keratinocytes and hasten re-epithelialization.

Resveratrol induces mitochondrial biogenesis and ameliorates Ang II-induced cardiac remodeling in transgenic rats harboring human renin and angiotensinogen genes.

There is compelling evidence to indicate an important role for increased local renin-angiotensin system activity in the pathogenesis of cardiac hypertrophy and heart failure. Resveratrol is a natural polyphenol that activates SIRT1, a novel cardioprotective and longevity factor having NAD(+)-dependent histone deacetylase activity. We tested the hypothesis whether resveratrol could prevent from angiotensin II (Ang II)-induced cardiovascular damage. Four-week-old double transgenic rats harboring human renin and human angiotensinogen genes (dTGR) were treated for 4 weeks either with SIRT1 activator resveratrol or SIRT1 inhibitor nicotinamide. Untreated dTGR and their normotensive Sprague-Dawley control rats (SD) received vehicle. Untreated dTGR developed severe hypertension as well as cardiac hypertrophy, and showed pronounced cardiovascular mortality compared with normotensive SD rats. Resveratrol slightly but significantly decreased blood pressure, ameliorated cardiac hypertrophy and prevented completely Ang II-induced mortality, whereas nicotinamide increased blood pressure without significantly influencing cardiac hypertrophy or survival. Resveratrol decreased cardiac ANP mRNA expression and induced cardiac mRNA expressions of mitochondrial biogenesis markers peroxisome proliferator-activated receptor-gamma coactivator (PGC-1alpha), mitochondrial transcription factor (Tfam), nuclear respiratory factor 1 (NRF-1) and cytochrome c oxidase subunit 4 (cox4). Resveratrol dose-dependently increased SIRT1 activity in vitro. Our findings suggest that the beneficial effects of SIRT1 activator resveratrol on Ang II-induced cardiac remodeling are mediated by blood pressure-dependent pathways and are linked to increased mitochondrial biogenesis.

Bcl-2 expression enhances myoblast sheet transplantation therapy for acute myocardial infarction.

Myoblast sheet transplantation is a promising novel treatment modality for heart failure after an ischemic insult. However, low supply of blood and nutrients may compromise sheet survival. The aim of this study was to investigate the effect of mitochondria-protective Bcl-2-modified myoblasts in cell sheet transplantation therapy. In the Bcl-2-expressing rat L6 myoblast sheets (L6-Bcl2), increased expression of myocyte markers and angiogenic mediators was evident compared to wild-type (L6-WT) sheets. The L6-Bcl2 sheets demonstrated significant resistance to apoptotic stimuli, and their differentiation capacity in vitro was increased. We evaluated the therapeutic effect of Bcl-2-modified myoblast sheets in a rat model of acute myocardial infarction (AMI). Sixty-four Wistar rats were divided into four groups. One group underwent AMI (n = 22), another AMI and L6-WT sheet transplantation (n = 17), and a third AMI and L6-Bcl2 sheet transplantation (n = 20). Five rats underwent a sham operation. Echocardiography was performed after 3, 10, and 28 days. Samples for histological analysis were collected at the end of the study. After AMI, the Bcl-2-expressing sheets survived longer on the infarcted myocardium, and significantly improved cardiac function. L6-Bcl2 sheet transplantation reduced myocardial fibrosis and increased vascular density in infarct and border areas. Moreover, the number of c-kit-positive and proliferating cells in the myocardium was increased in the L6-Bcl2 group. In conclusion, Bcl-2 prolongs survival of myoblast sheets, increases production of proangiogenic paracrine mediators, and enhances the therapeutic efficacy of cell sheet transplantation.