Miłosz P. Kawa

Complement system activation and endothelial dysfunction in patients with age‐related macular degeneration (AMD): possible relationship between AMD and atherosclerosis

Age‐related macular degeneration (AMD) shares several pathological and epidemiological similarities with systemic atherosclerosis (AS). First, an association between AS and AMD is apparent from the analyses of the histological and biochemical structure of atherosclerotic plaques in the vascular walls and retinal drusen, the hallmark of AMD. Second, there is considerable evidence implicating endothelial dysfunction in the pathogenesis of both disorders, and cellular oxidative stress appears to be a common denominator underlying this process. Moreover, there are observations that the complement system (CS) triggering inflammatory response contributes to the onset and advancement of both diseases. The CS plays a role in the generation of drusen and neovascularization in AMD as well as in vascular endothelium activation, cell damage and ultimately atherosclerotic plaque formation in the course of systemic arteriosclerosis. It is widely recognized that both AMD and AS are not only related to local stimulation of the CS, but also result in its systemic activation. In addition, a specific Y402H polymorphism of the complement inhibitor factor H has been found to be associated with the incidence of both AMD and AS. Here, we propose a linking hypothesis between CS activation, endothelial dysfunction and the pathogenesis of two common and age‐related pathological processes, AS and AMD. We also discuss the potential therapeutic value of pharmacological modulation of CS activation in these disorders.

Long-Term Neuroprotective Effects of NT-4-Engineered Mesenchymal Stem Cells Injected Intravitreally in a Mouse Model of Acute Retinal Injury

PURPOSE Retinal degenerative diseases targeting the RPE and adjacent photoreceptors affect millions of people worldwide. The field of stem cell- and gene-based therapy holds great potential for the treatment of such diseases. The present study sought to graft genetically engineered mesenchymal stem cells (MSCs) that continuously produce neurotrophin-4 (NT-4) into the murine eye after the onset of acute retinal injury. METHODS C57BL/6 mice were subjected to acute retinal damage using a low dose of sodium iodate (20 mg/kg of body weight), followed by intravitreal injection of lentivirally modified MSC-NT-4 into the right eye. At 3 months after the MSC transplantation grafted cell survival, retinal function and gene expression were analyzed. RESULTS Immunofluorescence analysis confirmed that transplanted MSCs survived for at least 3 months after intravitreal injection and preferentially migrated toward sites of injury within the retina. MSC-NT-4 actively produced NT-4 in the injured retina and significantly protected damaged retinal cells, as evaluated by ERG and optical coherence tomography (OCT). Of importance, the long-term therapy with MSC-NT-4 was also associated with induction of prosurvival signaling, considerable overexpression of some subsets of transcripts, including several members of the crystallin β-γ superfamily (Cryba4, Crybb3, Cryba2, Crybb1, Crybb2, Cryba1, and Crygc) and significant upregulation of biological processes associated with visual perception, sensory perception of light stimulus, eye development, sensory organ development, and system development. CONCLUSIONS Transplantation of genetically modified MSCs that produce neurotrophic growth factors may represent a useful strategy for treatment of different forms of retinopathies in the future.

The influence of 3,3′,5-triiodo-l-thyronine on human haematopoiesis

Abstract.  Objectives: Thyroid hormones mediate many physiological and developmental functions in humans. The role of the 3,3′,5‐triiodo‐l‐thyronine (T3) in normal human haematopoiesis at the cellular and molecular levels has not been determined. In this study, it was revealed that the human haematopoietic system might be directly depended on T3 influence. Materials and methods: We detected the TRα1 and TRβ1 gene expression at the mRNA level in human cord blood, peripheral blood and bone marrow CD34+‐enriched progenitor cells, using the RT‐PCR method. Furthermore, we performed Western blotting to prove TRα1 and TRβ1 expression occurs at the protein level in human cord blood, peripheral blood and bone marrow CD34+ cells. In addition, the examined populations of cells were exposed in serum‐free conditions to increasing doses of T3 and were subsequently investigated for clonogenic growth of granulocyte‐macrophage colony‐forming unit and erythrocyte burst‐forming unit in methylcellulose cultures, and for the level of apoptosis, by employing annexin V staining and the terminal deoxynucleotidyltransferase‐mediated dUTP nick‐end labelling method. We investigated expression levels of apoptosis‐related Bax and antiapoptotic Bcl‐2 and Bcl‐xL genes in the examined cells. Results: We found that exposure to higher and lower than normal concentration of thyroid hormone significantly influenced clonogenecity and induced apoptosis in human haematopoietic progenitor cells. Conclusions: This study expands the understanding of the role of thyroid disorders in normal human haematopoiesis and indicates a direct influence of T3 on this process.

Stem Cells are mobilized from the bone marrow into the peripheral circulation in response to retinal pigment epithelium damage--a pathophysiological attempt to induce endogenous regeneration.

Purpose: Stem cell regeneration of damaged tissue has recently been reported in many different organs. Here, we investigated the mobilization of different stem/progenitor cell (SPC) populations into the peripheral blood (PB), their subsequent homing to the injured retina (IR) and contribution to its regeneration in a retinal pigment epithelium (RPE) damage model induced by sodium iodate (NaIO3). Methods: Mobilization of SPCs was evaluated by flow cytometry. SPCs distribution in IR was assessed using bone marrow (BM)-derived GFP+Lin− cells transplanted intravenously into NaIO3-treated C57Bl/6 mice. The quantity of the chemokine SDF-1 in PB and IR was measured by ELISA and qRT-PCR, respectively. Apoptosis (TUNEL assay), cell proliferation (PCNA analysis) as well as functional retinal activity (electroretinogram) were examined at several time points after NaIO3 administration. Results: Mobilization of SPCs along with the highest cell proliferation and massive apoptosis within IR were observed on the third day after NaIO3 administration. Similarly, donor GFP+Lin− cells were detected in the retina as soon as day 4 after NaIO3 injection. Plasma levels of SDF-1 did not differ significantly in mice exposed to NaIO3 compared to healthy controls, however mRNA for SDF-1 was overexpressed locally in IR. Functional retinal recovery was not achieved. Conclusion: Our study provides evidence that BM SPCs egress into PB and home to the injured retina, but are not capable of restoring its function. These results indicate that if the range of retinal destruction is profound, endogenous regeneration is ineffective and may ultimately require adjuvant therapeutic transplantation of specific SPCs subpopulations.

Complement system in pathogenesis of AMD: dual player in degeneration and protection of retinal tissue.

Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly, especially in Western countries. Although the prevalence, risk factors, and clinical course of the disease are well described, its pathogenesis is not entirely elucidated. AMD is associated with a variety of biochemical abnormalities, including complement components deposition in the retinal pigment epithelium-Bruchs membrane-choriocapillaris complex. Although the complement system (CS) is increasingly recognized as mediating important roles in retinal biology, its particular role in AMD pathogenesis has not been precisely defined. Unrestricted activation of the CS following injury may directly damage retinal tissue and recruit immune cells to the vicinity of active complement cascades, therefore detrimentally causing bystander damage to surrounding cells and tissues. On the other hand, recent evidence supports the notion that an active complement pathway is a necessity for the normal maintenance of the neurosensory retina. In this scenario, complement activation appears to have beneficial effect as it promotes cell survival and tissue remodeling by facilitating the rapid removal of dying cells and resulting cellular debris, thus demonstrating anti-inflammatory and neuroprotective activities. In this review, we discuss both the beneficial and detrimental roles of CS in degenerative retina, focusing on the diverse aspects of CS functions that may promote or inhibit macular disease.

Circulating Stem Cell Populations in Preterm Infants: Implications for the Development of Retinopathy of Prematurity

OBJECTIVE To investigate the association among different circulating stem cell (SC) populations, the levels of selected growth factors and chemokines regulating SC migration in the peripheral blood, and the incidence of retinopathy of prematurity (ROP). METHODS We evaluated 88 participants in this study: 29 preterm infants with ROP, 29 preterm infants without ROP, and 30 healthy full-term infants. Peripheral blood samples collected 10 weeks after delivery were analyzed using flow cytometry, immunofluorescence, real-time reverse transcriptase-polymerase chain reaction, and enzyme-linked immunosorbent assay. The following cell populations were analyzed: (1) lin⁻CXCR4(+)CD45⁻ (enriched in very small embryonic-like SCs), (2) lin⁻CXCR4(+)CD45(+) (enriched in hematopoietic SCs), and (3) CD34(+)CD133(+)CD144(+) (early endothelial progenitor cells) [lin indicates lineage]. The concentrations of vascular endothelial growth factor, basic fibroblast growth factor, hepatocyte growth factor, and stromal cell-derived factor 1 were measured in the plasma. RESULTS The very small embryonic-like SCs and early endothelial progenitor cells expressing neural and endothelial markers were significantly increased in the preterm infants. The number of early endothelial progenitor cells in the peripheral blood was significantly greater in the preterm infants with ROP than in the preterm infants without ROP. An accompanying increase in the concentrations of vascular endothelial growth factor and hepatocyte growth factor was found in the peripheral blood of the preterm infants with ROP. No significant associations were found between hematopoietic SCs and ROP or prematurity. CONCLUSIONS The increased number of early endothelial progenitor cells along with elevated levels of vascular endothelial growth factor and hepatocyte growth factor in preterm infants with ROP suggest that circulating vasculogenic factors may play a role in the development and progression of ROP. The increased number of very small embryonic-like SCs in preterm infants suggests that the development of immature tissues and organs, including the retina, may require a contribution of circulating SCs.

Dose-Dependent Retinal Changes Following Sodium Iodate Administration: Application of Spectral-Domain Optical Coherence Tomography for Monitoring of Retinal Injury and Endogenous Regeneration

Abstract Background: The purpose of this study was to demonstrate the progression of acute retinal injury by correlating histological sections with in vivo spectral-domain optical coherence tomography (SD-OCT) images. Methods: Male C57BL/6 mice were treated intravenously with two different sodium iodate (NaIO3) doses (35 mg/kg or 15 mg/kg). In vivo SD-OCT was performed up to 3 months post-injury. Ex vivo retinal histology, TUNEL and IsolectinB4 immunostaining were also conducted. Quantitative comparison of histopathological images and SD-OCT images was performed. Results: SD-OCT examination revealed that administration of 35 mg/kg NaIO3 was associated with progressive and irreversible retinal degeneration. On day 3 post-injury, we found numerous apoptotic cells in the outer nuclear layer (ONL) that strongly corresponded to hyper-reflective areas in the SD-OCT images. At 7 d post-injury, SD-OCT images showed irregular-shaped patterns of hyper-reflectivity in the retinal pigment epithelium (RPE) that corresponded with the accumulation of macrophages phagocytosing melanin granules and cell debris. Additionally, we documented hyper-reflective opacities in the vitreous that were most numerous at 7 d. At 3 months post-injury, the neurosensory retina was significantly thinner, predominantly due to progressive photoreceptor (PR) loss. In contrast, administration of 15 mg/kg NaIO3 did not induce hyper-reflectivity of ONL in SD-OCT images, which indicates a lack of massive PR cell death. At 3 months post-injury, SD-OCT images showed the complete restoration of outer retina lamination and restoration of hyper-reflective structural bands. Histological assessment of retinas acquired after the last SD-OCT imaging session revealed complete regeneration of the RPE and considerable improvement of PR architecture. Conclusions: Our findings showed the high level of effectiveness of SD-OCT imaging for monitoring dynamic changes in retinal morphology following acute retinal injury. Moreover, we demonstrated for the first time that SD-OCT can be used to non-invasively detect regeneration in the damaged retina.

Humoral Activity of Cord Blood-Derived Stem/Progenitor Cells: Implications for Stem Cell-Based Adjuvant Therapy of Neurodegenerative Disorders

Background Stem/progenitor cells (SPCs) demonstrate neuro-regenerative potential that is dependent upon their humoral activity by producing various trophic factors regulating cell migration, growth, and differentiation. Herein, we compared the expression of neurotrophins (NTs) and their receptors in specific umbilical cord blood (UCB) SPC populations, including lineage-negative, CD34+, and CD133+ cells, with that in unsorted, nucleated cells (NCs). Methods and Results The expression of NTs and their receptors was detected by QRT-PCR, western blotting, and immunofluorescent staining in UCB-derived SPC populations (i.e., NCs vs. lineage-negative, CD34+, and CD133+ cells). To better characterize, global gene expression profiles of SPCs were determined using genome-wide RNA microarray technology. Furthermore, the intracellular production of crucial neuro-regenerative NTs (i.e., BDNF and NT-3) was assessed in NCs and lineage-negative cells after incubation for 24, 48, and 72 h in both serum and serum-free conditions. We discovered significantly higher expression of NTs and NT receptors at both the mRNA and protein level in lineage-negative, CD34+, and CD133+ cells than in NCs. Global gene expression analysis revealed considerably higher expression of genes associated with the production and secretion of proteins, migration, proliferation, and differentiation in lineage-negative cells than in CD34+ or CD133+ cell populations. Notably, after short-term incubation under serum-free conditions, lineage-negative cells and NCs produced significantly higher amounts of BDNF and NT-3 than under steady-state conditions. Finally, conditioned medium (CM) from lineage-negative SPCs exerted a beneficial impact on neural cell survival and proliferation. Conclusions Collectively, our findings demonstrate that UCB-derived SPCs highly express NTs and their relevant receptors under steady-state conditions, NT expression is greater under stress-related conditions and that CM from SPCs favorable influence neural cell proliferation and survival. Understanding the mechanisms governing the characterization and humoral activity of subsets of SPCs may yield new therapeutic strategies that might be more effective in treating neurodegenerative disorders.

Circulating hematopoietic stem cell count is a valuable predictor of prematurity complications in preterm newborns

BackgroundThe frequency of preterm labour has risen over the last few years. Hence, there is growing interest in the identification of markers that may facilitate prediction and prevention of premature birth complications. Here, we studied the association of the number of circulating stem cell populations with the incidence of complications typical of prematurity.MethodsThe study groups consisted of 90 preterm (23–36 weeks of gestational age) and 52 full-term (37–41 weeks) infants. Non-hematopoietic stem cells (non-HSCs; CD45-lin-CD184+), enriched in very small embryonic-like stem cells (VSELs), expressing pluripotent (Oct-4, Nanog), early neural (β-III-tubulin), and oligodendrocyte lineage (Olig-1) genes as well as hematopoietic stem cells (HSCs; CD45+lin-CD184+), and circulating stem/progenitor cells (CSPCs; CD133+CD34+; CD133-CD34+) in association with characteristics of prematurity and preterm morbidity were analyzed in cord blood (CB) and peripheral blood (PB) until the sixth week after delivery. Phenotype analysis was performed using flow cytometry methods. Clonogenic assays suitable for detection of human hematopoietic progenitor cells were also applied. The quantitative parameters were compared between groups by the Mann–Whitney test and between time points by the Friedman test. Fisher’s exact test was used for qualitative variables.ResultsWe found that the number of CB non-HSCs/VSELs is inversely associated with the birth weight of preterm infants. More notably, a high number of CB HSCs is strongly associated with a lower risk of prematurity complications including intraventricular hemorrhage, respiratory distress syndrome, infections, and anemia. The number of HSCs remains stable for the first six weeks of postnatal life. Besides, the number of CSPCs in CB is significantly higher in preterm infants than in full-term neonates (p < 0.0001) and extensively decreases in preterm babies during next six weeks after birth. Finally, the growth of burst-forming unit of erythrocytes (BFU-E) and colony-forming units of granulocyte-macrophage (CFU-GM) obtained from CB of premature neonates is higher than those obtained from CB of full-term infants and strongly correlates with the number of CB-derived CSPCs.ConclusionWe conclude that CB HSCs are markedly associated with the development of premature birth complications. Thus, HSCs ought to be considered as the potential target for further research as they may be relevant for predicting and controlling the morbidity of premature infants. Moreover, the observed levels of non-HSCs/VSELs circulating in CB are inversely associated with the birth weight of preterm infants, suggesting non-HSCs/VSELs might be involved in the maturation of fetal organism.

Neuroprotective and antiapoptotic activity of lineage-negative bone marrow cells after intravitreal injection in a mouse model of acute retinal injury.

We investigated effects of bone marrow-derived, lineage-negative cell (Lin−BMC) transplantation in acute retinal injury. Lin−BMCs were intravitreally injected into murine eyes at 24 h after NaIO3-induced injury. Morphology, function, and expression of apoptosis-related genes, including brain-derived neurotrophic factor (BDNF) and its receptor, were assessed in retinas at 7 days, 28 days, and 3 months after transplantation. Moreover, global gene expression at day 7 was analyzed by RNA arrays. We observed that Lin−BMCs integrated into outer retinal layers improving morphological retinal structure and induced molecular changes such as downregulation of proapoptotic caspase-3 gene, a decrease in BAX/BCL-2 gene ratio, and significant elevation of BDNF expression. Furthermore, transplanted Lin−BMCs differentiated locally into cells with a macrophage-like phenotype. Finally, Lin−BMCs treatment was associated with generation of two distinct transcriptomic patterns. The first relates to downregulated genes associated with regulation of neuron cell death and apoptosis, response to oxidative stress/hypoxia and external stimuli, and negative regulation of cell proliferation. The second relates to upregulated genes associated with neurological system processes and sensory perception. Collectively, our data demonstrate that transplanted Lin−BMCs exert neuroprotective function against acute retinal injury and this effect may be associated with their antiapoptotic properties and ability to express neurotrophic factors.