Function Of Donor Age Research Articles

Successful In Vitro Shoot Multiplication of Quercus robur L. Trees Aged up to 800 Years.

The conservation of the genetic resources of old trees is crucial to their ecological role but is extremely difficult, especially for oak species (Quercus spp.) displaying recalcitrance in seed and vegetative propagation methods. Our study aimed to assess the regenerative potential of Quercus robur trees of different ages (up to 800 years) during micropropagation. We also aimed to determine how in vitro conditions can influence in vitro regeneration responses. Lignified branches collected from 67 selected trees were cultivated ex vitro in culture pots at 25 °C to obtain epicormic shoots (explant sources). The explants were cultivated on an agar medium supplemented with 0.8 mg L-1 6-benzylaminopurine (BAP) for at least 21 months. In a second experiment, two different shoot multiplication conditions (temporary immersion-RITA® bioreactor and agar medium) and two culture medium formulations (Woody Plant Medium and modified Quoirin and Lepoivre medium) were tested. The results showed that the mean length of the epicormic shoots obtained in a pot culture was a function of donor age and was similar among the group of younger trees (ca. 20-200 years), and varied between older trees (ca. 300-800 years). The efficiency of in vitro shoot multiplication strictly depended on the genotype. A sustainable in vitro culture (defined as survival after 6 months) was only possible for half of the tested old donor trees, even when they survived the first month of in vitro growth. A continuous monthly increase in the number of in vitro cultured shoots was reported in younger oaks and in some old oaks. We found a significant effect of the culture system and the macro- and micronutrient composition on in vitro shoot growth. This is the first report demonstrating that the in vitro culture can be successfully applied to the propagation of even 800-year-old pedunculate oak trees.

Mirages - REDS Explorer: An Online Portal for Longitudinal Metabolomics Data from the REDS-III RBC Omics Study

Over one hundred million units of packed red blood cells (pRBCs) are stored and transfused annually around the world. Storage of pRBCs in the blood bank contributes to a series of biochemical and morphological changes in pRBCs, collectively referred to as the "storage lesion(s)", that ultimately impact RBC capacity to circulate in the bloodstream of recipients, carry and deliver oxygen. A growing body of studies has shown that the metabolism of pRBCs is affected by storage duration, processing strategies, as well as donor exposures ("exposome"). The latter include diet; consumption of alcohol, caffeinated beverages; smoking; and use of medications that do not result in donor deferral. Furthermore donor genetics (e.g., sex, ethnicity, G6PD status and many other genetic traits in RBC proteins) and other biological factors (e.g., age, body mass index [BMI]) impact pRBC storage and transfusion efficacy. Despite significant advances in the characterization of the storage lesion, most omics studies have been limited in scale to tens of pRBC units. These studies thus failed to grasp the extent to which donor biology, processing strategies or other factors (exposures) impact the metabolic age of stored units (as opposed to the chronological age - i.e., days elapsed since donation). As such, it remains unclear whether or to what extent the molecular make up of a unit correlates to its hemolytic propensity and post-transfusion efficacy. To bridge this gap, we leveraged the Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P), a research program aimed at improving blood donor safety and optimizing transfusion outcomes. Overall, 97% (13,403) of the whole blood donations provided by 13,758 donors age 18+ who provided informed consent at four different blood centers across the US were evaluable for hemolysis parameters, including spontaneous and stress (oxidative and osmotic) hemolysis analysis in ~42-day stored RBC derived from 8,502 whole blood donations. A total of 643 donors scoring in the 5th and 95th percentile for hemolysis parameters were invited to donate a second unit of pRBCs, which were assayed at storage days 10, 23 and 42 for hemolytic parameters and mass spectrometry-based high-throughput metabolomics. A pilot study was performed on 599 samples as part of the REDS-III RBC Omics project, while the whole recalled donor cohort was assayed as part of REDS-IV-P, for a total of serial 1,929 samples. As part of the MIRAGES project (Metabolic Investigation of Red blood cells, as a function of Aging, Genetics, Environment and Storage), we generated the REDS Explorer portal, for real time data processing and visualization. The portal not only serves as the largest online metabolomics data repository in transfusion medicine, but also affords data elaborations, including correlations to biological characteristics (donor sex, age, BMI, blood group, Rh status), processing strategies (additive solutions, blood center, irradiation) and functional readouts (ferritin levels, hemolytic parameters). The user can adjust for relevant covariates, select specific ranges for variables such as age, and filter based on donor sex, additive solution or storage duration - while choosing between the REDS III pilot data or the REDS-IV-P full recalled donor cohort. The portal generates publication quality figures for free, direct download. For example, here we show that L-citrulline is a previously unappreciated marker of blood donor age increasing in pRBCs as a function of donor age (Figure 1.A-B - q=3.84 e-24), with opposite trends observed for hydroxyisovaleryl-carnitine (q = 3.55 e-11 Figure 1.C). The latter was then identified as the top positive correlate to donor ferritin levels at the time of donation (q = 1.47 e-16 - Figure 1.D). The portal facilitates generation and investigation of new data-driven hypotheses, enabling the rapid dissemination and/or further mechanistic testing, thus maximizing the value of large-scale initiatives such as REDS-III/IV-P. The blood donor population as a window on the larger healthy population, high-throughput metabolomics applications in transfusion medicine, and the MIRAGES: REDS Explorer portal are directly relevant to advances in the fields of epidemiology and hematology. Figure 1 - Example of an output from the MIRAGES - REDS Explorer portal - based on donor age and ferritin levelsFigure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Age-dependent dysregulation of redox genes may contribute to fibrotic pulmonary disease susceptibility

Aging is associated with enhanced oxidative stress and increased susceptibility to numerous diseases. This relationship is particularly striking with respect to the incidence of fibrotic lung disease. To identify potential mechanisms underlying the association between aging and susceptibility to fibrotic lung disease we analyzed transcriptome data from 342 disease-free human lung samples as a function of donor age. Our analysis reveals that aging in lung is accompanied by modest yet progressive changes in genes modulating redox homeostasis, the TGF-beta 1 signaling axis, and the extracellular matrix (ECM), pointing to an aging lung functional network (ALFN). Further, the transcriptional changes we document are tissue-specific, with age-dependent gene expression patterns differing across organ systems. Our findings suggest that the age-associated increased incidence of fibrotic pulmonary disease occurs in the context of tissue-specific, age-dependent transcriptional changes. Understanding the relationship between age-associated gene expression and susceptibility to fibrotic pulmonary disease may allow for more accurate risk stratification and effective therapeutic interventions within this challenging clinical space.

Liver Transplantation Results by Donor Age

ObjectiveThe objective of this study was to compare liver transplantation outcomes as a function of donor age. Material and MethodsWe performed 212 liver transplantations between 2008 and 2014. We described a prospective cohort study and grouped the patients by liver donor age. We compared quantitative and categorical variables using statistical analysis. ResultsNo statistically significant differences were found among any graft age groups in gender (always more males), time on waiting list, age, height, Child Pugh Turcotte (CHILD) score, Model for End-stage Liver Disease (MELD) score, need for intraoperative blood products, or intensive care unit stay. The most frequent etiology of liver failure was alcohol. A brain-dead donor was the most frequent type in all groups. The whole graft was used except in 4 cases. No statistically significant differences were found among groups in the surgical technique, postreperfusion syndrome, arterial complications, biliary complications, venous complications, acute rejection, and retransplantation. The 3-year patient survival rate was 64% in the <60-year graft age group, 48% in the 60- to 69-year group, 64% in the 70- to 79-year group, and 40% in the ≥80-year group (P = .264). The 3-year graft survival rate was 62% in the <60-year graft age group, 47% in the 60- to 69-year group, 65% in the 70- to 79-year group, and 40% in the ≥80-year group (P = .295). ConclusionsGiven the need to increase the pool of liver donors, older donors should be considered as a source for liver transplantation, although careful selection is required.

Effects of Donor Age, Long-Term Passage Culture, and Cryopreservation on Tonsil-Derived Mesenchymal Stem Cells

Objectives: Human mesenchymal stem cells (MSCs) are efficacious in various cellular therapeutic applications and have been isolated from several tissues. Recent studies have reported that human tonsil tissue contains a new source of progenitor cells, potentially applicable for cell-based therapies. Information about the effects of donor age, long-term passage and cryopreservation are essential for clinical applications and cell-based therapies. Therefore, the authors investigated how the morphology, cell-surface markers, proliferation potential and differentiation capacity of tonsil-derived MSCs (T-MSCs) were affected by donor age, long-term passage, and cryopreservation. Materials and Methods: T-MSCs were isolated from tonsillar tissue of 20 patients undergoing tonsillectomy. Authors evaluated the effects of donor-age, long-term passage, and cryopreservation on the morphology, surface markers, proliferation potential and differentiation capacities of T-MSCs. Results: T-MSCs exhibited a fibroblast-like, spindle-shaped appearance. There were no significant morphological differences according to donor age, long-term passage or cryopreservation. T-MSCs isolated from donors of various ages were positive for markers CD90, CD44, and CD73, but negative for CD45, CD31, and HLA-DR. There were no significant differences in the expression of positive and negative surface markers as a function of donor age, long-term passage and cryopreservation. T-MSCs from different donor age groups showed similar proliferation potentials after passage 2. After long-term passage and cryopreservation, there were no significant morphological differences. Cryopreservation did not affect the proliferation potential of T-MSCs, but there was a significant decrease in the proliferation potential in long-term passage T-MSCs (passage 15). The effect of donor age, long-term passage and cryopreservation on the in vitro adipogenic, osteogenic, and chondrogenic differentiation potential of T-MSCs was not significant. Conclusion: The effect of donor age, long-term passage culture, and cryopreservation on T-MSC properties are negligible, except for the proliferation capacity of long-term cultured T-MSCs. Therefore, T-MSCs are considered to be promising MSCs that can be used as future alternative sources for autologous or allogenic MSCs.

The importance of mesenchymal stem cell donor’s age for cartilage engineering

In 1994, Brittber et coll. showed that cultured autologous chondrocytes could be used to repair deep cartilage defects of the knee joint. But, several problems are observed due to the differentiation of chondrocytes in culture leading to fibrocartilage formation. More recently, the use of bone marrow mesenchymal stem cells (BM-MSC) in cartilage engineering has been used. As hinted by the role of stem cell senescence and dysfunction in natural aging, donor or patient age will be a critical factor that must be accounted for in clinical and laboratory evaluations of bone marrow mesenchymal stem cell based technology.We evaluated in vitro chondrogenic differentiation of bone marrow mesenchymal stem cells in function of donor age and passage in culture. The objective of such a study design was to provide a controlled analysis of two variables (age and passage) and possible interaction between these crucial factors in developing adult stem cell based therapeutics and for which no consensus exists regarding their role in MSC differentiation. Materials and Methods: Mesenchymal stem cells were obtained from bone marrow from human donors of different ages (n = 18, 3 to 85 years old, mean age 49 ± 27). Cells were isolated by plastic adherence (5 104 mononuclear cells/cm2) and cultured in α-MEM with 10% SVF. After two weeks cells were detached from culture flasks and replated at 1000 cells/cm2. Then cells were passaged every two weeks. At each passage, cells were counted, clonogenicity was tested by a colony forming unit test and phenotype was verified by flow cytometry for the expression of several markers (CD90, CD73, CD105, CD44, CD45, CD34, HLA-DR). Chondrogenic potential was assayed after passage 1 and 4/5 using specific differentiation media containing TGF-β. 2.5 x 105 cells were used to form each chondrogenic pellet. After 28 days, Gene expression of chondrogenic markers was evaluated by qPCR and matrix synthesis by histology and alcian blue staining. Quantification of staining area was performed by using ImageJ. Results: Our study has revealed differences between proliferation capacities of BM-MSC in function of donor’s age. Cells from old donors proliferate slowly than cells from young donors and become senescent after 4 or 5 passages. Two groups of donors have been defined according to proliferation capacity (less than 40 years old and over 40 years old). Phenotype, clonogenicity and chondrogenic differentiation was studied in the two groups. While cells expressed mesenchymal markers (CD90, CD44, CD73, CD105) and did not expressed HLA-DR, CD45 or CD34, no differences were observed in the expression level of the markers according to donor’s age. Clonogenicity was inceased for cells coming from young donors, both at number or size levels. At the same time, young donors cells were characterized by high level expression of type 2 collagen, aggrecan and sox-9 genes after chondrogenic differentiation while cells from the > 40 years group showed a poor chondrogenic differentiation. Similar results were observed at the matrix synthesis levels after alcian blue staining. Cells from late passages showed decresed differentiation compared with cells from early passages. However, at early passages, cells from young donors presented a great differentiation potential than cells from aged donors. Conclusions: This study shows that differences on proliferation and chondrogenic differentiation exist between mesenchymal stem cells isolated from bone marrow obtained in young and old donors. These results could be considered in the choice of MSC for cartilage tissue engineering. The proliferation capacity of cells and their clonogenicity are good parameters to rapidly estimate cell quality.

The use of lung donors older than 55 years: A review of the United Network of Organ Sharing database

Current lung transplantation guidelines stipulate that the ideal donor is aged younger than 55 years, but several institutions have reported that outcomes using donors aged 55 years and older are comparable with those of younger donors. We retrospectively reviewed the United Network for Organ Sharing (UNOS) database to identify all adult lung transplants between 2000 and 2010 in the United States. Patients were stratified by donor age 18 to 34 (reference), 35 to 54, 55 to 64, and ≥ 65 years. Primary outcomes included survival at 30 days and at 1, 3, and 5 years and rates of bronchiolitis obliterans syndrome (BOS). Survival was assessed using the Kaplan-Meier method. Risk factors for mortality were identified by multivariable Cox and logistic regression. We identified 10,666 recipients with median follow-up of 3 years (range, 0-10 years). Older donors were more likely to have died of cardiovascular or cerebrovascular causes, but there were no differences in recipient diagnosis, lung allocation score, or incidence of BOS as a function of donor age. The use of donors aged 55 to 64 years was not a risk factor for mortality at 1 year (odds ratio, 1.1; p = 0.304) or 3 years (odds ratio, 0.923; p = 0.571) compared with the reference group; however, use of donors aged > 65 years was associated with increased mortality at both time points (odds ratio, 2.8 and 2.4, p < 0.02). Outcomes after lung transplantation using donors aged 55 to 64 years were similar to those observed with donors meeting conventional age criteria. Donors aged ≥ 65 years, however, were associated with decreased intermediate-term survival, although there was no increased risk of BOS for this group.

Functional Comparison of Chronological and In Vitro Aging: Differential Role of the Cytoskeleton and Mitochondria in Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) are of high relevance for the regeneration of mesenchymal tissues such as bone and cartilage. The promising role of MSCs in cell-based therapies and tissue engineering appears to be limited due to a decline of their regenerative potential with increasing donor age, their limited availability in human tissues and the need of in vitro expansion prior to treatment. We therefore aimed to determine to which degree in vitro aging and chronological aging may be similar processes or if in vitro culture-related changes at the cellular and molecular level are at least altered as a function of donor age. For that purpose we established MSCs cultures from young (yMSCs) and aged (aMSCs) rats that were cultured for more than 100 passages. These long-term MSCs cultures were non-tumorigenic and exhibited similar surface marker patterns as primary MSCs of passage 2. During in vitro expansion, but not during chronological aging, MSCs progressively lose their progenitor characteristics, e.g., complete loss of osteogenic differentiation potential, diminished adipogenic differentiation, altered cell morphology and increased susceptibility towards senescence. Transcriptome analysis revealed that long-term in vitro MSCs cultivation leads to down-regulation of genes involved in cell differentiation, focal adhesion organization, cytoskeleton turnover and mitochondria function. Accordingly, functional analysis demonstrated altered mitochondrial morphology, decreased antioxidant capacities and elevated ROS levels in long-term cultivated yMSCs as well as aMSCs. Notably, only the MSC migration potential and their antioxidative capacity were altered by in vitro as well as chronological aging. Based on specific differences observed between the impact of chronological and in vitro MSC aging we conclude that both are distinct processes.

Stem Cell Sources for Vascular Tissue Engineering and Regeneration

This review focuses on the stem cell sources with the potential to be used in vascular tissue engineering and to promote vascular regeneration. The first clinical studies using tissue-engineered vascular grafts are already under way, supporting the potential of this technology in the treatment of cardiovascular and other diseases. Despite progress in engineering biomaterials with the appropriate mechanical properties and biological cues as well as bioreactors for generating the correct tissue microenvironment, the source of cells that make up the vascular tissues remains a major challenge for tissue engineers and physicians. Mature cells from the tissue of origin may be difficult to obtain and suffer from limited proliferative capacity, which may further decline as a function of donor age. On the other hand, multipotent and pluripotent stem cells have great potential to provide large numbers of autologous cells with a great differentiation capacity. Here, we discuss the adult multipotent as well as embryonic and induced pluripotent stem cells, their differentiation potential toward vascular lineages, and their use in engineering functional and implantable vascular tissues. We also discuss the associated challenges that need to be addressed in order to facilitate the transition of this technology from the bench to the bedside.

Living Donor Age and Kidney Allograft Half-Life

Living donor paired exchange programs assume that kidneys from living donors are of comparable quality and anticipated longevity. This study determined actual allograft t(1/2) within different recipient age groups (10-year increments) as a function of donor age (5-year increments), and juxtaposed these results against the probabilities of deceased donor transplantation, and exclusion from transplantation (death or removal from the wait-list). Data from the US Renal Data System (transplant dates 1988-2003 with follow-up through September 2007) were used to determine allograft t(1/2), whereas data from patients on the United Network for Organ Sharing waiting list between 2003 and 2005 (with follow-up through February 2010) were used to determine wait-list outcomes. With the exception of recipients aged 18-39 years, who had the best outcomes with donors aged 18-39 years, living donor age between 18 and 64 years had minimal effect on allograft t(1/2) (difference of 1-2 years with no graded association). The probability of deceased donor transplantation after 3 years of wait-listing ranged from 21% to 66% by blood type and level of sensitization, whereas the probability of being excluded from transplantation ranged from 6% to 27% by age, race, and primary renal disease. With the exception of recipients aged 18-39 years, living donor age between 18 and 64 years has minimal effect on allograft survival.

Collagen Turnover in Normal and Degenerate Human Intervertebral Discs as Determined by the Racemization of Aspartic Acid

Knowledge of rates of protein turnover is important for a quantitative understanding of tissue synthesis and catabolism. In this work, we have used the racemization of aspartic acid as a marker for the turnover of collagen obtained from healthy and pathological human intervertebral disc matrices. We measured the ratio of the d- and l-isomers in collagen extracted from these tissues as a function of age between 16 and 77 years. For collagen taken from healthy discs, the fractional increase of d-Asp was found to be 6.74 x 10(-4)/year; for degenerate discs, the corresponding rate was 5.18 x 10(-4)/year. Using the racemization rate found previously for the stable population of collagen molecules in dentin, we found that the rate of collagen turnover (k(T)) in discs is not constant but rather a decreasing function of age. The average turnover rate in normal disc between the ages of 20 and 40 is 0.00728 +/- 0.00275/year, and that between the ages of 50 and 80 is 0.00323 +/- 0.000947/year, which correspond to average half-lives of 95 and 215 years, respectively. Turnover of collagen from degenerate discs may be more rapid than that found for normal discs; however, statistical analysis leaves this point uncertain. The finding of a similar correlation between the accumulation of d-Asp and that of pentosidine for three normal collagenous tissues further supports the idea that the accumulation of pentosidine in a particular tissue can, along with the racemization of aspartic acid, be used as a reliable measure of protein turnover.

H1 histone subtype constitution and phosphorylation state of the ageing cell system of human peripheral blood lymphocytes

Until a few years ago, the H1 histones were exclusively considered to be the architectural proteins of chromatin involved in chromatin condensation. However there is now increasing data to support the hypothesis that the H1 subtypes are involved in genomic integrity and that they may have unexpected functional roles in various biological processes such as in differentiation and DNA repair, apoptosis and lifespan. Moreover, the H1 histones are phosphorylated to a great extent. Recent work has implicated phosphorylation of H1 in the regulation of chromatin remodeling. In light of the fact that chromatin reorganization and heterochromatin formation has been shown to take place during ageing and senescence, in the present investigation, we have analyzed the changes that take place in the somatic H1 linker histone subtype profile and their phosphorylation states in human peripheral blood lymphocytes as a function of donor age. Results from this work show that there is a significant age-related dephosphorylation of H1.4 and H1.5 and an increase in the heterochromatin protein HP1α as a function of donor age. These results indicate that dephosphorylation of H1 histones may be related to an increase in senescence-associated heterochromatin formation during the in vivo ageing of human peripheral blood lymphocytes.

Effect of the Histone Deacetylase Inhibitor Trichostatin A in Human Peripheral Blood Lymphocytes as a Function of Donor Age

The histone deacetylase inhibitor trichostatin A (TSA) is a promising agent for the treatment of certain types of cancers alone or in synergistic combination with other anticancer agents. One of the advantages of the use of histone deacetylase inhibitors, such as TSA, is that its effects have been found to be more potent toward cancer cells compared to normal cells. The effect of anticancer agents on the immune system, and on lymphocytes in particular, is of major importance to the success of anticancer regimens. In this respect, information documenting the effect of such agents on normal lymphocytes compared to malignant cells may be of significant value for the successful designing of clinical protocols. Moreover, the parameter of age may be a factor in the differential effects of such protocols. Histone deacetylase inhibitors lead to the accumulation of acetylated histones and, depending on the cell type, may induce either apoptosis, cell cycle arrest, or differentiation. Previous work from our lab has shown that TSA induces the accumulation of histone H4 acetylation and apoptosis in human peripheral blood lymphocytes. In light of the above, we have extended our investigation of the effects of TSA on human lymphocytes to include the parameter of age, which has not been previously studied. Our results show that TSA induces apoptosis of lymphocytes from donors of all age groups, but no age-related changes in the levels of apoptosis are observed.

Older Donor Livers Show Early Severe Histological Activity, Fibrosis, and Graft Failure After Liver Transplantation for Hepatitis C

In hepatitis C virus (HCV)-positive liver transplant recipients, infection of the allograft and recurrent liver disease are important problems. Increased donor age has emerged as an important variable affecting patient and graft survival; however, specific age cutoffs and risk ratios for poor histologic outcomes and graft survival are not clear. A longitudinal database of all HCV-positive patients transplanted at our center during an 11-year period was used to identify 111 patients who received 124 liver transplants. Graft survival and histological endpoints (severe activity and fibrosis) of HCV infection in the allografts were compared as a function of donor age at transplantation. By Kaplan-Meier analyses, older allografts showed earlier failure and decreased time to severe histological activity and fibrosis as compared with allografts from younger donors. By Cox proportional hazards analysis, older allografts were at greater risk for all severe histologic features and decreased graft survival as compared with younger allografts (P< or =0.02 for all outcomes). Analysis of donor age as a dichotomous variable showed that donors greater than 60 yr were at high risk for deleterious histologic outcomes and graft failure. An age cutoff of 60 yr showed a sensitivity of 94% and specificity of 67% for worse graft survival by receiver operating characteristics curve. Advanced donor age is associated with more aggressive recurrent HCV and early allograft failure in HCV-positive liver transplant recipients. Consideration of donor age is important for decisions regarding patient selection, antiviral therapy, and organ allocation.

The Older Living Kidney Donor: Part of the Solution to the Organ Shortage

Strategies to increase kidney transplantation are urgently needed. We studied all (n = 73,073) first kidney-only transplant recipients in the United States between 1995 and 2003 to determine the incidence and outcomes of living donor transplantation as a function of donor age. Because 90% of living donors were <55 years, we defined older living donors as > or =55 years. Factors associated with transplantation from older living donors and the association of living donor age with allograft function and survival were determined. Recipients of older age, female gender, white race, and preemptive transplants had higher odds of older living donor transplantation. Older living donor transplantation was more likely from spousal donors rather than blood relatives, and more likely when a husband was the donor. The glomerular filtration rate (GFR) one year after transplantation decreased with increasing donor age (P < 0.001). Graft survival from living donors > or =55 years was 85% and 76% at three and five years (compared to 89% and 82% with living donors <55 years, and 82% and 73% with deceased donors <55 years). In a multivariate model, the risk of graft loss with living donors 55-64 years was similar to that with deceased donors <55 years, while recipients from living donors 65-69 years (HR = 1.3, 95% CI: 1.1-1.7) and >70 years (HR = 1.7, 95% CI: 1.1-2.6) had a higher relative risk of graft loss. Outcomes are excellent with living donors <65 years. Expanded use of older living donors may help meet the demand for transplantation.

Donor age as a predictor of cornea transplant success

Background: The purpose of this study was to examine the association between donor age and cornea transplant success. Methods: This retrospective cohort study comprised 116 patients who had cornea transplants performed for the first time. The primary analysis was performed to evaluate the time to graft failure as a function of donor age. Donor age was divided into 3 categories: (1) continuous, (2) younger than 65 versus 65 years and older, and (3) younger than 60 versus older than 70 years. We controlled for other variables that may affect graft outcome by multivariate modeling. The primary outcome was graft failure. Results: No statistically significant association was found between time to failure and donor age [adjusted hazard ratio: 1.004 ( p = 0.68) for continuous age, 1.18 ( p = 0.68) for age < 65 vs. ≥ 65 years, and 2.10 ( p = 0.089) for age < 60 vs. > 70 years]. However, with all model-building strategies, our results demonstrated that all hazard ratios calculated were greater than 1.00 for the older versus the younger aged groups. Interpretation: The influence of donor age on success of cornea transplants remains unresolved. Large, multicentre prospective cohort studies and randomized trials are needed to decisively determine the impact of donor age on cornea transplant success.

Age-dependent response of lymphocytes in the induction of the linker histone variant, H1° and histone H4 acetylation after treatment with the histone deacetylase inhibitor, trichostatin A

In the present study we investigated the age-related response of Phytohemaglutinin (PHA)-activated S phase human lymphocytes isolated from peripheral blood from donors of four different age groups, namely young (25–30 years), mid-aged (40–45 years), senior (60–65 years) and elderly (80–95 years) on the induction of the linker histone variant, H1° and histone H4 acetylation after treatment with the very specific histone deacetylase (HDAC) inhibitor, trichostatin A (TSA). The cell system of peripheral blood lymphocytes is ideal for the study of H1° induction since they do not synthesize this particular linker histone variant. Lymphocytes isolated from peripheral blood were activated with PHA (5 μg/10 6 cells/ml medium) and placed in culture for a duration of 72 h at which time cells are in the S phase. Forty-eight hours after inoculation, TSA (250 ng/10 6 cells/ml medium) was added to the cell cultures for a period of 24 h. Assays were performed 72 h after initiation of cultures. The results showed that the induction of H1° after TSA treatment increased to a statistically significant degree in the elderly age group with respect to both the young and the mid-aged age groups. Moreover histone H4 acetylation was found to increase as a function of increasing donor age. A hyperacetylation pattern was observed even in the youngest age group analyzed. Specifically, the tetra-acetylated (H4.4) H4 form increased to a statistically significant degree with the concomitant decrease in the non-acetylated H4 for (H4.0) as a function of donor age. The other acetylated H4 forms (H4.1, H4.2, and H4.3) remained more or less constant, irrespective of donor age. These results show that the sensitivity of lymphocytes to TSA is enhanced with increasing donor age. Since to date, 11 class I and II HDACs have been isolated that have been found by other investigators to have differential responses to HDAC inhibitors, these findings may indicate that there is also a differential age-related response of certain HDACs or perhaps a senescent-specific HDAC. This line of research warrants further study.

Basis for the age-related decline in intestinal mucosal immunity.

The elderly are characterized by mucosal immunosenescence and high rates of morbidity and mortality associated with infectious diseases of the intestinal tract. Little is known about how the differentiation of immunoglobulin A (IgA) plasma cells in Peyer's patches (PPs) and their subsequent homing to the small intestinal lamina propria (LP) is affected by aging. Quantitative immunohistochemical analyses demonstrated a 2-fold increase in the number of IgA+ cells in the PPs, coupled with significant declines in the numbers of IgA+ and antibody-positive cells in the intestinal LP of senescent rats compared to young adult animals. These data suggest that aging diminishes the emigration of IgA immunoblasts from these lymphoid aggregates, as well as their migration to the intestinal LP. Flow cytometry and lymphocyte adoptive transfer studies showed 3- to 4-fold age-related declines in the homing of antibody-containing cells and mesenteric lymph node lymphocytes to the small intestines of rhesus macaques and rats, respectively. The number of peripheral blood IgA immunoblasts expressing the homing molecule α4β7 declined 30% in senescent rats. This was accompanied by a >17% decrease in the areal density of LP blood vessels staining positive for the cell adhesion molecule MAdCAM-1. Cumulatively, declines in expression of these homing molecules constitute a substantial age-related diminution of IgA immunoblast homing potential. In vitro antibody secretion by LP plasma cells, i.e. antibody secreted per antibody-positive cell, remains unchanged as a function of donor age. Intestinal mucosal immunosenescence is a consequence of reduced homing of IgA plasma cells to the intestinal LP as a result of declines in homing molecule expression.

Prevalence and quantitation of species C adenovirus DNA in human mucosal lymphocytes.

The common species C adenoviruses (serotypes Ad1, Ad2, Ad5, and Ad6) infect more than 80% of the human population early in life. Following primary infection, the virus can establish an asymptomatic persistent infection in which infectious virions are shed in feces for several years. The probable source of persistent virus is mucosa-associated lymphoid tissue, although the molecular details of persistence or latency of adenovirus are currently unknown. In this study, a sensitive real-time PCR assay was developed to quantitate species C adenovirus DNA in human tissues removed for routine tonsillectomy or adenoidectomy. Using this assay, species C DNA was detected in Ficoll-purified lymphocytes from 33 of 42 tissue specimens tested (79%). The levels varied from fewer than 10 to greater than 2 x 10(6) copies of the adenovirus genome/10(7) cells, depending on the donor. DNA from serotypes Ad1, Ad2, and Ad5 was detected, while the rarer serotype Ad6 was not. When analyzed as a function of donor age, the highest levels of adenovirus genomes were found among the youngest donors. Antibody-coated magnetic beads were used to purify lymphocytes into subpopulations and determine whether viral DNA could be enriched within any purified subpopulations. Separation of T cells (CD4/8- expressing and/or CD3-expressing cells) enriched viral DNA in each of nine donors tested. In contrast, B-cell purification (CD19-expressing cells) invariably depleted or eliminated viral DNA. Despite the frequent finding of significant quantities of adenovirus DNA in tonsil and adenoid tissues, infectious virus was rarely present, as measured by coculture with permissive cells. These findings suggest that human mucosal T lymphocytes may harbor species C adenoviruses in a quiescent, perhaps latent form.

The effect of donor age on the sensitivity of osteoblasts to the proliferative effects of TGF β and 1,25(OH 2) vitamin D 3

The loss of osteoblast function in aging bone is one of the major causes of osteopenia, or loss of bone mass. In this study, this loss of function was investigated by examining the proliferative response of rat long bone periosteal osteoblasts to TGF β1 and 1,25-dihydroxy vitamin D 3 (1,25-D 3) as a function of donor age. Using a DNA binding fluorescent dye, DNA levels were measured in osteoblast cultures derived from either young adult (3–4 months) or old (14–15 months) rats following treatment with two concentrations (10 −9 M or 10 −12 M) of either 1,25-D 3 or TGF β1 or with vehicle. Cells from young rat bone, when treated with 1, 25-D 3, showed a dose-dependent increase in proliferation when treated with the higher dose and a decrease in proliferation when treated with the lower dose. Osteoblasts isolated from old rats did not respond to 1, 25-D 3 treatment. A similar pattern of response to TGF β1 was found. When treated with 10 −9 M TGF β1, the rate of proliferation increased for young rat osteoblasts, but the old rat derived cells were unresponsive. The 10 −12 M dose of TGF β1 was ineffective for both young and old cells. This study has shown that osteoblasts derived from old donors are impaired in their ability to respond to vitamin D and TGF β, two of the major controlling factors of skeletal development and maintenance.