Stem Cell Aging

Stem cells persist throughout life, replacing cells lost to homeostatic turnover, injury, and disease. However, their functions decline with age, which contributes to degeneration and dysfunction. The molecular mechanisms involved in the aging of stem cells are the same as the ones involved in the aging of somatic cells, including telomere shortening, oxidative stress, epigenetic dysregulation, miRNAs changes, alterations of DNA, RNA, proteome, and various cellular organelles. Aging impacts various pathways, such as insulin/insulin-like growth factor 1 (IGF-1), mTOR, FoxO, AMP-activated protein kinase (AMPK), sirtuin, and many others, resulting in senescent stem cells that exhibit functional and numerical impairment. Stem cells have developed special mechanisms to prevent age related damage accumulation and to sustain their stemness properties, however, these mechanisms lose their effectiveness over time. The most fatal consequence of this is found in the immune system, where both innate and adaptive immunity are affected, exhibiting a plethora of defects, including increased autoimmune disease occurrence, elevated tolerance to cancer and chronic inflammatory status. Stem cell therapies call for the best quality of stem cells grafts. Stem cell products should be devoid of cells containing a senescent phenotype, thus a comprehensive knowledge of the biology behind the senescence of stem cells should be taken into account in every cell based therapy

The Influence of Allogeneic Platelet Gel on the Morphology of Human Long Bones

The aim of this study is to analyze the morphologic and functional change of human bone defect after its grafting with mixture of platelet gel and autologous cancellous bone. For one year, we have prospectively studied nine consecutive patients, aged 25-73 y, with pseudoarthrosis of long bones, after unsuccessful initial surgeries. We have harvested cancellous bone from patients’ iliac crests and mixed with the ABO compatible allogeneic platelet rich plasma (PRP) gel. That mixture has been inserted in the bone defect, and surgically fixated. Radiologically, the defects achieved the bone morphology (the appearance of hazy callus) between 6th and 24th week. The time of functional recovery was varied, between 12 and 40 weeks for partial weight bearing, and between 16 and 48 weeks for free limb mobility and full function of the limb. The overall healing of bone defect was 16 to 36 weeks. Two patients had complications of poor graft ingrowth and one with a reversible postsurgical nerve paresis. On the X-ray scans, solid and fast restoration of bone structure was notable, with excellent bone ingrowth, suitable for full weight bearing. The allogeneic platelet gel had no adverse effects. This method can be used for treating of long bone defects, because of its strong influence on restoration of normal bone morphology. Further investigation is required to establish efficiency relative to other methods

The Influence of Allogeneic Platelet Gel on the Morphology of Human Long Bones

The aim of this study is to analyze the morphologic and functional change of human bone defect after its grafting with mixture of platelet gel and autologous cancellous bone. For one year, we have prospectively studied nine consecutive patients, aged 25-73 y, with pseudoarthrosis of long bones, after unsuccessful initial surgeries. We have harvested cancellous bone from patients’ iliac crests and mixed with the ABO compatible allogeneic platelet rich plasma (PRP) gel. That mixture has been inserted in the bone defect, and surgically fixated. Radiologically, the defects achieved the bone morphology (the appearance of hazy callus) between 6th and 24th week. The time of functional recovery was varied, between 12 and 40 weeks for partial weight bearing, and between 16 and 48 weeks for free limb mobility and full function of the limb. The overall healing of bone defect was 16 to 36 weeks. Two patients had complications of poor graft ingrowth and one with a reversible postsurgical nerve paresis. On the X-ray scans, solid and fast restoration of bone structure was notable, with excellent bone ingrowth, suitable for full weight bearing. The allogeneic platelet gel had no adverse effects. This method can be used for treating of long bone defects, because of its strong influence on restoration of normal bone morphology. Further investigation is required to establish efficiency relative to other methods

Induction of Tolerogenic Dendritic Cells by Endogenous Biomolecules: An Update

The importance of microenvironment on dendritic cell (DC) function and development has been strongly established during the last two decades. Although DCs with general tolerogenic characteristics have been isolated and defined as a particular sub-population, it is predominantly their unequivocal biological plasticity, which allows for unparalleled responsiveness to environmental ques and shaping of their tolerogenic characteristics when interacting with tolerance-inducing biomolecules. Dendritic cells carry receptors for a great number of endogenous factors, which, after ligation, can importantly influence the development of their activation state. For this there is ample evidence merely by observation of DC characteristics isolated from various anatomical niches, e.g., the greater immunosuppressive potential of DCs isolated from intestine compared to conventional blood DCs. Endogenous biomolecules present in these environments most likely play a major role as a determinant of their phenotype and function. In this review, we will concisely summarize in what way various, tolerance-inducing endogenous factors influence DC biology, the development of their particular tolerogenic state and their subsequent actions in context of immune response inhibition and induction of regulatory T cells

A “Crossomics” Study Analysing Variability of Different Components in Peripheral Blood of Healthy Caucasoid Individuals

Background: Different immunotherapy approaches for the treatment of cancer and autoimmune diseases are being developed and tested in clinical studies worldwide. Their resulting complex experimental data should be properly evaluated, therefore reliable normal healthy control baseline values are indispensable. Methodology/Principal Findings: To assess intra- and inter-individual variability of various biomarkers, peripheral blood of 16 age and gender equilibrated healthy volunteers was sampled on 3 different days within a period of one month. Complex "crossomics'' analyses of plasma metabolite profiles, antibody concentrations and lymphocyte subset counts as well as whole genome expression profiling in CD4(+)T and NK cells were performed. Some of the observed age, gender and BMI dependences are in agreement with the existing knowledge, like negative correlation between sex hormone levels and age or BMI related increase in lipids and soluble sugars. Thus we can assume that the distribution of all 39.743 analysed markers is well representing the normal Caucasoid population. All lymphocyte subsets, 20% of metabolites and less than 10% of genes, were identified as highly variable in our dataset. Conclusions/Significance: Our study shows that the intra- individual variability was at least two-fold lower compared to the inter-individual one at all investigated levels, showing the importance of personalised medicine approach from yet another perspective

Uspješnost liječenja kroničnih rana alogenim trombocitnim gelom u usporedbi s hidrogelom: prospektivno istraživanje

The aim of the study was to evaluate the efficacy and safety of the new method of platelet-rich plasma activation in the form of platelet gel, used in the treatment of non-healing ­chronic lower leg ulcers. The study was prospectively randomized, double blind and placebo controlled. We treated 60 patients (42 males and 18 females, mean age 69.43 years, SD 14.74) with chronic lower leg ulcers of different etiologies. Thirty patients were treated with allogeneic platelet gel and 30 with ­hydrogel. Both groups were comparable for duration of ulcer and its size. Treatment was repeated once a week for three consecutive weeks and then the last examination was scheduled at 6 months of the first platelet gel application. The t-test was used to analyze independent samples. Healing of chronic wounds with platelet gel was statistically significantly more effective compared to the treatment with hydrogel (p<0.05). At 6 months of platelet gel application, the mean wound area in the experimental group decreased to 35.01% (SD 53.69) of the initial wound size. In the control group, the wound area decreased to 89.95% (SD 71.82) of the initial wound size (p=0.001). The circumference of the wounds diminished to 54.62% (SD 39.85) of the initial value in the experimental group, compared to 91.28% (SD 29.32) in the control group (p<0.001). Allogeneic platelet gel prepared by the new ­method used in this study was found to be a good treatment option for non-healing chronic wounds when other methods are ineffective.Cilj ove studije bio je procijeniti djelotvornost i sigurnost nove metode aktivacije plazme bogate trombocitima u obliku trombocitnog gela koji se rabi za liječenje kroničnih ulkusa potkoljenice koji ne cijele. Studija je bila prospektivno randomizirana, dvostruko slijepa i placebom kontrolirana. Liječili smo 60 bolesnika (42 muškarca, 18 žena, srednje dobi od 69,43 godine, SD 14,74) s kroničnim ulkusima potkoljenice različitih etiologija. Po 30 bolesnika liječeno je alogenim trombocitnim gelom odnosno hidrogelom. Obje skupine bile su usporedive po trajanju ulkusa i njegovoj veličini. Liječenje se ponavljalo jednom tjedno tijekom tri uzastopna tjedna i tada je posljednji pregled obavljen 6 mjeseci od prve primjene trombocitnog gela. Za analizu nezavisnih uzoraka primijenjen je t-test. Liječenje kroničnih rana trombocitnim gelom bilo je statistički značajno učinkovitije u odnosu na liječenje hidrogelom (p<0,05). Šest mjeseci nakon aplikacije gela srednja vrijednost površine rana u eksperimentalnoj skupini smanjila se na 35,01% (SD 53,69) početne veličine rane. U kontrolnoj skupini područje rana smanjilo se na 89,95% (SD 71,82), p=0,001. Opseg rana smanjio se na 54,62% (SD 39,85) početne vrijednosti u eksperimentalnoj skupini u usporedbi s 91,28% (SD 29,32) u kontrolnoj skupini (p<0,001). Alogeni trombocitni gel pripremljen novom metodom koja se rabila u ovom istraživanju dobar je izbor za liječenje kroničnih rana koje ne cijele kada druge metode nisu učinkovite

Regeneration of Chronic Wounds with Allogeneic Platelet Gel versus Hydrogel Treatment: a Prospective Study

The aim of the study was to evaluate the efficacy and safety of the new method of platelet-rich plasma activation in the form of platelet gel, used in the treatment of non-healing ­chronic lower leg ulcers. The study was prospectively randomized, double blind and placebo controlled. We treated 60 patients (42 males and 18 females, mean age 69.43 years, SD 14.74) with chronic lower leg ulcers of different etiologies. Thirty patients were treated with allogeneic platelet gel and 30 with ­hydrogel. Both groups were comparable for duration of ulcer and its size. Treatment was repeated once a week for three consecutive weeks and then the last examination was scheduled at 6 months of the first platelet gel application. The t-test was used to analyze independent samples. Healing of chronic wounds with platelet gel was statistically significantly more effective compared to the treatment with hydrogel (p<0.05). At 6 months of platelet gel application, the mean wound area in the experimental group decreased to 35.01% (SD 53.69) of the initial wound size. In the control group, the wound area decreased to 89.95% (SD 71.82) of the initial wound size (p=0.001). The circumference of the wounds diminished to 54.62% (SD 39.85) of the initial value in the experimental group, compared to 91.28% (SD 29.32) in the control group (p<0.001). Allogeneic platelet gel prepared by the new ­method used in this study was found to be a good treatment option for non-healing chronic wounds when other methods are ineffective