Human blood and marrow side population stem cell and Stro-1 positive bone marrow stromal cell numbers decline with age, with an increase in quality of surviving stem cells: correlation with cytokines

The heterogeneity of mesenchymal stem cells: an important issue to be addressed in cell therapy

With the continuous improvement of human technology, the medical field has gradually moved from molecular therapy to cellular therapy. As a safe and effective therapeutic tool, cell therapy has successfully created a research boom in the modern medical field. Mesenchymal stem cells (MSCs) are derived from early mesoderm and have high self-renewal and multidirectional differentiation ability, and have become one of the important cores of cell therapy research by virtue of their immunomodulatory and tissue repair capabilities. In recent years, the application of MSCs in various diseases has received widespread attention, but there are still various problems in the treatment of MSCs, among which the heterogeneity of MSCs may be one of the causes of the problem. In this paper, we review the correlation of MSCs heterogeneity to provide a basis for further reduction of MSCs heterogeneity and standardization of MSCs and hope to provide a reference for cell therapy.

Washed microbiota transplantation improves haemoglobin levels in anaemia of chronic disease

BACKGROUND

Anaemia of chronic disease (ACD) is the second most common type of anaemia and lacks an effective treatment. Patients with anaemia are reported to have altered gut microbial profiles, which may affect erythropoiesis. Here, we investigated the gut microbial features of patients with ACD and determined whether regulating gut microbiota using washed microbiota transplantation (WMT) was effective in treating ACD.

METHODS

We compared the gut microbiota profile of patients with ACD and healthy controls, evaluated the efficacy of WMT on haematological parameters in the patients, and analysed the alterations in gut microbiota after WMT treatment.

RESULTS

Patients with ACD had lower gut microbial richness, and differences in microbial composition and function, relative to healthy controls. Additionally, the relative abundances of two butyrate-producing genera Lachnospiraceae NK4A136 group and Butyricicoccus, were positively correlated with the haemoglobin (HGB) level and lower in patients with ACD than controls. WMT significantly increased HGB levels in patients with ACD. After the first, second and third WMT rounds, normal HGB levels were restored in 27.02%, 27.78% and 36.37% (all p < .05) of patients with ACD, respectively. Moreover, WMT significantly increased the abundance of butyrate-producing genera and downregulated gut microbial functions that were upregulated in patients with ACD.

CONCLUSIONS

Patients with ACD exhibited differences in gut microbial composition and function relative to healthy controls. WMT is an effective treatment for ACD that reshapes gut microbial composition, restores butyrate-producing bacteria and regulates the functions of gut microbiota.

Progression of Carotid Intima-Media Thickness Partly Indicates the Prevention of Hypertension among Older Individuals in the General Population

Structural atherosclerosis, as evaluated by carotid intima-media thickness (CIMT), is reported to be positively associated with hypertension. However, angiogenesis, which plays an important role in the progression of structural atherosclerosis, prevents hypertension by reducing peripheral vascular resistance. These associations evoke a contradiction: characteristics associated with the progression of structural atherosclerosis, which is related to hypertension, might prevent hypertension. To clarify novel mechanisms underlying the association between structural atherosclerosis and hypertension, multifaceted analyses are necessary. We performed several epidemiological studies based on this concept. This study summarizes those epidemiological studies and adds some discussion. Studies focusing on circulating CD34-positive cells, single-nucleotide polymorphisms (SNPs) of vascular endothelial growth factor (VEGF), SNPs in BRACA1-associated protein (BRAP), platelets, human T-cell leukemia virus type 1 (HTLV-1), and SNPs in aldehyde dehydrogenase 2 (ALDH2) have shown that active endothelial repair, which leads to the progression of structural atherosclerosis, helps prevent hypertension. These associations indicate that the progression of structural atherosclerosis could act as a marker of angiogenesis, which reduces peripheral vascular resistance. In general, a positive association between structural atherosclerosis and hypertension has been reported. However, the progression of structural atherosclerosis could act as a marker of activity that prevents hypertension via reductions in peripheral vascular resistance.

Low-Density Lipoprotein Cholesterol, Structural Atherosclerosis, and Functional Atherosclerosis in Older Japanese

Aggressive endothelial repair results in the progression of both structural and functional atherosclerosis, while insufficient endothelial repair worsens functional but not structural atherosclerosis. Aging increases the risk of inadequate endothelial repair. Since low-density lipoprotein cholesterol (LDLc) activates endothelial repair, LDLc may be positively associated with structural atherosclerosis but inversely associated with functional atherosclerosis in older individuals. This cross-sectional study analyzed 1458 participants aged 60 to 79 years. We defined structural atherosclerosis as a carotid intima-media thickness (CIMT) of at least 1.1 mm and functional atherosclerosis as a cardio-ankle vascular index (CAVI) of at least 9.0. LDLc was significantly positively associated with structural atherosclerosis and significantly inversely associated with functional atherosclerosis, independently of known cardiovascular risk factors. For 1 standard increment of LDLc (28 mg/dL for men and 29 mg/dL for women), the odds ratios and 95% confidence intervals after adjustment for known cardiovascular risk factors were 1.28 (1.10, 1.50) for structural atherosclerosis and 0.85 (0.75, 0.96) for functional atherosclerosis. LDLc activates endothelial repair, which results in the development of structural atherosclerosis but maintains endothelial function in older individuals. To evaluate atherosclerosis in clinical practice, the combination of structural and functional assessment of atherosclerosis could be informative.

Mechanism underlying vascular remodeling in relation to circulating CD34-positive cells among older Japanese men

Development of structural atherosclerosis, an established cardiovascular risk factor, requires hematopoietic stem cells known as CD34-positive cells. However, an inverse association between circulating CD34-positive cell count and cardiovascular disease has been reported. These studies evoke a contradiction: characteristics associated with a low risk of developing structural atherosclerosis are also associated with a high risk of cardiovascular disease. To clarify the mechanisms underlying vascular remodeling, we conducted several epidemiological studies of Japanese men aged 60 to 69 years who participated in annual health check-ups. The present study summarizes those epidemiological studies and adds some discussion. From the perspective of endothelial repair activity, there are significant differences between functional versus structural atherosclerosis. Aggressive endothelial repair increases both functional and structural atherosclerosis. Deficient endothelial repair related to a shortage of CD34-positive cells due to consumption furthers functional atherosclerosis but not structural atherosclerosis. Therefore, the lack of structural atherosclerosis does not always reflect a favorable condition for the endothelium. Although further investigation is necessary, the present study suggests that higher endothelial repair activity that leads to structural atherosclerosis might have a beneficial effect on vascular health among older men.

Height and Active Arterial Wall Thickening in Relation to Thyroid Cysts Status among Elderly Japanese: A Prospective Study

Height is inversely associated with inflammation that stimulates endothelial repair. In our previous study involving elderly men aged 60-69 years, we found that active arterial wall thickening, which is known as the process of endothelial repair, requires CD34-positive cells. As thyroid hormone regulates CD34-positive cell production and as the absence of thyroid cysts might indicate latent damage in the thyroid, the status of thyroid cysts possibly influences the association between height and active arterial wall thickening. We conducted a 2-year follow-up study of Japanese aged 60-69 years. For participants with thyroid cysts, height was significantly inversely associated with active arterial wall thickening (thyroid function and baseline CIMT adjusted odds ratio of active arterial wall thickening for one increment of standard deviation of height (5.7 cm for men and 4.8 cm for women), 0.66 [0.49, 0.89]), while for those without thyroid cysts, a positive tendency between the two parameters was observed (1.19 [0.96, 1.50]). An inverse association between height and active arterial wall thickening was observed only for elderly participants with thyroid cysts possibly because of a supportive role of thyroid hormone, as the absence of thyroid cysts might indicate latent damage in the thyroid.

Immunosenescence in Childhood Cancer Survivors and in Elderly: A Comparison and Implication for Risk Stratification

The population of childhood cancer survivors (CCS) has grown rapidly in recent decades. Although cured of their original malignancy, these individuals are at increased risk of serious late effects, including age-associated complications. An impaired immune system has been linked to the emergence of these conditions in the elderly and CCS, likely due to senescent immune cell phenotypes accompanied by low-grade inflammation, which in the elderly is known as "inflammaging." Whether these observations in the elderly and CCS are underpinned by similar mechanisms is unclear. If so, existing knowledge on immunosenescent phenotypes and inflammaging might potentially serve to benefit CCS. We summarize recent findings on the immune changes in CCS and the elderly, and highlight the similarities and identify areas for future research. Improving our understanding of the underlying mechanisms and immunosenescent markers of accelerated immune aging might help us to identify individuals at increased risk of serious health complications.

Topical growth factors and home-based microneedling for facial skin rejuvenation

BACKGROUND

Cosmeceutical products are an important therapeutic option for facial rejuvenation. Of these, topical application of growth factors has been shown to increase dermal collagen synthesis, improve skin texture, and reduce fine lines and wrinkles. Limited data exist for the use of growth factors in combination with microneedling.

OBJECTIVE

This prospective, single-center, uncontrolled study evaluated the efficacy of topical growth factor treatment in conjunction with transdermal delivery of growth factors via home-based microneedling for facial skin rejuvenation.

PATIENTS/METHODS

Eleven healthy female individuals aged 33-61 years, with mild-moderate facial wrinkling were included in the study. Over 3 months, participants received twice-daily application of a topical recombinant human growth factor preparation (SkinGenuity^® Regenerative and Reparative Serums) along with twice-weekly transdermal delivery of growth factors using a home-based microneedling (0.2 mm) device. Objective skin analysis (VISIA^® ) and a subjective patient-reported outcome (FACE-Q^® ) assessment measuring satisfaction with appearance were performed at baseline and after 3 months.

RESULTS

Objective skin analysis showed a significant improvement in skin texture (17.6%, p < 0.001), wrinkles (17.3%, p < 0.001), red areas (12.4%, p =0.004), and brown spots (6.0%, p =0.03) at 3 months follow-up. FACE-Q scales showed a significant improvement from baseline, including satisfaction with skin, facial appearance, nasolabial folds, cheeks, and lower face/jawline (all p ≤ 0.02). Numerical improvement in adverse effects related to skin was also observed (p = 0.07). No serious adverse effects were reported.

CONCLUSIONS

Three months of twice-daily topical growth factor treatment in conjunction with transdermal delivery of growth factors via microneedling improved skin analysis parameters and participant-reported outcome measures, indicative of facial skin rejuvenation.

Patient Age and Cell Concentration Influence Prevalence and Concentration of Progenitors in Bone Marrow Aspirates: An Analysis of 436 Patients

BACKGROUND

Connective tissue progenitors (CTPs) resident in native tissues serve as biological building blocks in tissue repair and remodeling processes. Methods for analysis and reporting on CTP quantity and quality are essential for defining optimal cell sources and donor characteristics and the impact of cell processing methods for cell therapy applications. The present study examines the influence of donor characteristics and cell concentration (nucleated cells/mL) on CTP prevalence (CTPs/million nucleated cells) and CTP concentration (CTPs/mL) in bone marrow aspirates (BMAs).

METHODS

Iliac crest bone marrow was aspirated from 436 patients during elective total knee or hip arthroplasty. Bone marrow-derived nucleated cells were plated at a density of 1.19 × 105 cells/cm2. Colony-forming unit analysis was performed on day 6.

RESULTS

Large variation was seen between donors. Age (p < 0.05) and cell concentration (p < 0.001) significantly influenced CTP prevalence and CTP concentration. For every 1-year increase in age, the odds of having at least an average CTP prevalence and CTP concentration decreased by 1.5% and 1.6%, respectively. For every 1 million cells/mL increase in cell concentration, the odds of having at least an average CTP prevalence and CTP concentration increased by 2.2% and 7.9%, respectively. Sex, race, body mass index (BMI), and the presence of osteoporosis did not influence CTP prevalence or CTP concentration.

CONCLUSIONS

BMA-derived CTPs were obtained from all patient groups. CTP prevalence and CTP concentration decreased with age. Cell concentration decreased with age and positively correlated with total CTP prevalence and CTP concentration. The mean CTP concentration in patients >60 years of age was a third of the CTP concentration in patients <30 years of age.

CLINICAL RELEVANCE

Proper BMA techniques are necessary to obtain a high-quality yield and composition of cells and CTPs. The reduced CTP concentration and CTP prevalence in the elderly may be mitigated by the use of cell processing methods that increase CTP concentration and CTP prevalence (e.g., by removing red blood cells, serum, and non-CTPs or by increasing aspirate volumes). Cell concentration in the BMA can be measured at the point of care and is an appropriate initial assessment of the quality of BMA.

Associations between handgrip strength and hypertension in relation to circulating CD34-positive cell levels among Japanese older men: a cross-sectional study

Background

A positive association between handgrip strength and blood pressure has been reported. Since these factors are linked to the condition of the endothelium, the activity of endothelial repair might influence the association between handgrip strength and hypertension.

Methods

A cross-sectional study was conducted with 257 Japanese men aged 60–69 years who underwent an annual health checkup. As individuals with high level of circulating CD34-positive cells might show active endothelial repair, which plays an important role in vascular homeostasis, participants were stratified by circulating CD34-positive cell levels, using the median value of this population (0.96 cells/μL) as the cutoff.

Results

Independent of known cardiovascular risk factors, for participants with a high CD34-positive cell, handgrip strength is significantly positively associated with hypertension (odds ratio and 95% confidence interval of hypertension for 1 standard deviation increment of handgrip strength were 1.85 (1.19, 2.88) but not for participants with a low CD34-positive cell (0.91 (0.61, 1.37)).

Conclusion

The positive association between handgrip strength and hypertension is limited to high CD34-positive cells. This result may help clarify the role of vascular homeostasis in maintaining muscle strength.

Inflammation rapidly recruits mammalian GMP and MDP from bone marrow into regional lymphatics

Innate immune cellular effectors are actively consumed during systemic inflammation, but the systemic traffic and the mechanisms that support their replenishment remain unknown. Here, we demonstrate that acute systemic inflammation induces the emergent activation of a previously unrecognized system of rapid migration of granulocyte-macrophage progenitors and committed macrophage-dendritic progenitors, but not other progenitors or stem cells, from bone marrow (BM) to regional lymphatic capillaries. The progenitor traffic to the systemic lymphatic circulation is mediated by Ccl19/Ccr7 and is NF-κB independent, Traf6/IκB-kinase/SNAP23 activation dependent, and is responsible for the secretion of pre-stored Ccl19 by a subpopulation of CD205+/CD172a+ conventional dendritic cells type 2 and upregulation of BM myeloid progenitor Ccr7 signaling. Mature myeloid Traf6 signaling is anti-inflammatory and necessary for lymph node myeloid cell development. This report unveils the existence and the mechanistic basis of a very early direct traffic of myeloid progenitors from BM to lymphatics during inflammation.

Contribution of VEGF polymorphism rs3025020 to short stature and hypertension in elderly Japanese individuals: a cross-sectional study

Background

Recently, short stature has been revealed to be positively associated with hypertension, possibly because this indicates lower activity of vascular maintenance, such as angiogenesis. Vascular endothelial growth factor (VEGF) polymorphism (rs3025020) plays an important role in the progression of angiogenesis and may be associated with both hypertension and hypertension-associated short stature.

Methods

A cross-sectional study of 1377 elderly Japanese individuals aged 60–89 years was conducted. Short stature was defined as the lowest tertile of height (< 160.8 cm for men and < 148.7 cm for women). Hypertension was defined as systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg and/or antihypertensive medication use.

Results

Independent of known cardiovascular risk factors, short stature was found to be positively associated with hypertension; the fully adjusted odds ratio (OR) and 95% confidence interval (CI) for hypertension were 1.51 (1.17, 1.96). With the reference group of carriers of the major allele of rs3025020, TT-homozygotes showed significantly lower OR for hypertension and short stature; the fully adjusted ORs (and 95% CIs) were 0.60 (0.41, 0.90) for hypertension and 0.59 (0.38, 0.91) for short stature, respectively.

Conclusions

Angiogenesis-related genetic factor (rs3025020) is associated with hypertension and short stature, whereas short stature is positively associated with hypertension. Further investigation is necessary in this regard; the capacity for angiogenesis might partly explain the mechanism underlying the inverse association between height and hypertension.

The local concentration of Ca2+ correlates with BMP7 expression and osseointegration in patients with total hip arthroplasty

BACKGROUND

A successful osseointegration of total hip arthroplasty (THA) relies on the interplay of implant surface and bone marrow microenvironment. This study was undertaken to investigate the impact of perioperative biochemical molecules (Ca²⁺, Mg²⁺, Zn²⁺, VD, PTH) on the bone marrow osteogenetic factors (BMP2, BMP7, Stro-1⁺ cells) in the metaphyseal region of the femoral head, and further on the bone mineral density (BMD) of Gruen R3.

METHODS

Bone marrow aspirates were obtained from the discarded metaphysis region of the femoral head in 51 patients with THA. Flow cytometry was used to measure the Stro-1⁺ expressing cells. ELISA was used to measure the concentrations of bone morphologic proteins (BMP2 and BMP7) and the content of TRACP5b in serum. TRAP staining was used to detect the osteoclast activity in the hip joint. The perioperative concentrations of the biochemical molecules above were measured by radioimmunoassay. The BMD of Gruen zone R3 was examined at 6 months after THA, using dual-energy X-ray absorptiometry (DEXA).

RESULTS

Our data demonstrated that the concentration of Ca²⁺ was positively correlated with BMP7 expression, and with the postoperative BMD of Gruen zone R3. However, the concentration of Mg²⁺ had little impact on the R3 BMD, although it was negatively correlated with the expression of BMP7. Osteoclast activity in hip joint tissue of patients with femoral neck fractures was increased. Compared with the patients before THA, the levels of TRACP5b in serum of patients after THA were decreased. The data also suggested that the other biochemical molecules, such as Zn²⁺, VD, and PTH, were not significantly correlated with any bone marrow osteogenetic factors (BMP2, BMP7, Stro-1⁺ cells). The postoperative R3 BMD of patients of different gender and age had no significant difference.

CONCLUSIONS

These results indicate the local concentration of Ca²⁺ may be an indicator for the prognosis of THA patients.

Association between height and circulating CD34-positive cells taken into account for the influence of enhanced production among elderly Japanese men: a cross-sectional study

Recent studies have revealed an inverse association between height and cardiovascular disease and that endothelial progenitor cells (CD34-positive cells) contribute to vascular maintenance, which is associated with cardiovascular disease. However, evidence of the association between height and CD34-positive positive cells among elderly participants is limited. To assess this association, we conducted a cross-sectional study of 231 elderly Japanese men aged 65–69. Since enhanced production of circulating CD34-positive cells in response to endothelial injury might act have a strong confounding effect on the association between height and circulating CD34-positive cells, the median value for the levels of these cells (0.93 cells/μL) was used to stratify the participants. Multivariable linear regression analysis demonstrated that height was significantly positively associated with circulating CD34-positive cells for those participants with low levels of circulating CD34-positive cells (n=114) but not for those with higher levels (n=117), with a multi-adjusted standardized parameter estimate (β) of 0.27 (p=0.008) for low and 0.11 (0.275) for higher circulating CD34-positive cell levels. The positive association is limited to participants with relatively low circulating CD34-positive cell levels, whose productivity of these cells is not activated. Our findings indicate that height is an indicator of vascular maintenance capability in elderly Japanese men.

Circulating CD34+ cells and active arterial wall thickening among elderly men: A prospective study

Age-related physical changes, such as low-grade inflammation and increased oxidative stress, induce endothelial repair and cause active arterial wall thickening by stimulating the production of CD34+ cells (the principal mediators of atherosclerosis). Despite this, aggressive endothelial repair (progressing atherosclerosis) might cause a wasting reduction in CD34+ cells, which could result in a lower capacity of endothelial repair and hypertension. As yet, no prospective study has clarified the association of circulating CD34+ cells with active arterial wall thickening. We conducted a prospective study of 363 men aged 60-69 years who participated in a general health check-up at least twice from 2014-2017. The circulating CD34+ cell count was significantly positively associated with active arterial wall thickening among subjects without hypertension (n = 236), but not among subjects with hypertension (n = 127). The fully adjusted odds ratios (ORs) of active arterial wall thickening for the logarithmic circulating CD34+ cell count were 1.83 (1.19, 2.84) and 0.69 (0.36, 1.32) for subjects without and with hypertension, respectively. Circulating CD34+ cells are positively associated with active arterial wall thickening in subjects without hypertension. This study demonstrates a means to clarify the mechanisms of endothelial repair in elderly subjects.

Gamma-glutamyl transpeptidase (γ-GTP) has an ambivalent association with hypertension and atherosclerosis among elderly Japanese men: a cross-sectional study

Background

Even though there is bidirectional association between hypertension and atherosclerosis, atherosclerosis itself is involved in the process of endothelial repair. To clarify the association of endothelial repair with hypertension, a cross-sectional study was conducted.

Methods

We conducted a cross-sectional study of 562 elderly Japanese men aged 60–69. As gamma-glutamyl transpeptidase (γ-GTP) could act as a marker of oxidative stress that injures endothelial cell and higher levels of CD34-positive cell indicate a higher activity of endothelial repair, we therefore performed a CD34-positive level specific analysis of γ-GTP on atherosclerosis and hypertension.

Results

In the present study population, hypertension was independently and positively associated with atherosclerosis (multivariable odds ratio (OR) = 2.09 (1.30, 3.35)). Among participants with high CD34-positive cells, γ-GTP showed significant and positive association with atherosclerosis (OR of the log-transformed value of γ-GTP (OR) = 2.26 (1.32, 3.86)) but not with hypertension (OR = 0.77 (0.51, 1.17)). Among participants with low CD34-positive cells, even γ-GTP showed no significant association with atherosclerosis (OR = 0.92 (0.51, 1.68)), but was significantly and positively associated with hypertension (OR = 1.99 (1.27, 3.12)).

Conclusions

γ-GTP revealed to have ambivalent association with hypertension and atherosclerosis. Active endothelial repair that is associated with atherosclerosis might have beneficial association with hypertension.

Remodeling of Bone Marrow Hematopoietic Stem Cell Niches Promotes Myeloid Cell Expansion during Premature or Physiological Aging

Hematopoietic stem cells (HSCs) residing in the bone marrow (BM) accumulate during aging but are functionally impaired. However, the role of HSC-intrinsic and -extrinsic aging mechanisms remains debated. Megakaryocytes promote quiescence of neighboring HSCs. Nonetheless, whether megakaryocyte-HSC interactions change during pathological/natural aging is unclear. Premature aging in Hutchinson-Gilford progeria syndrome recapitulates physiological aging features, but whether these arise from altered stem or niche cells is unknown. Here, we show that the BM microenvironment promotes myelopoiesis in premature/physiological aging. During physiological aging, HSC-supporting niches decrease near bone but expand further from bone. Increased BM noradrenergic innervation promotes β2-adrenergic-receptor(AR)-interleukin-6-dependent megakaryopoiesis. Reduced β3-AR-Nos1 activity correlates with decreased endosteal niches and megakaryocyte apposition to sinusoids. However, chronic treatment of progeroid mice with β3-AR agonist decreases premature myeloid and HSC expansion and restores the proximal association of HSCs to megakaryocytes. Therefore, normal/premature aging of BM niches promotes myeloid expansion and can be improved by targeting the microenvironment.

The Analysis of In Vivo Aging in Human Bone Marrow Mesenchymal Stromal Cells Using Colony-Forming Unit-Fibroblast Assay and the CD45lowCD271+ Phenotype

Uncultured mesenchymal stromal cells (MSCs) are increasingly used in therapies; however, the effects of donor age on their biological characteristics and gene expression remain unclear. The aim of this study was to investigate age-related changes in bone marrow (BM) MSCs following minimal or no culture manipulation. Iliac crest BM was aspirated from 67 healthy donors (19-89 years old) and directly used for the colony-forming unit-fibroblast (CFU-F) assay or CD45^lowCD271⁺ cell enumeration. The colonies were analysed for colony area and integrated density (ID) when grown in standard MSC media or media supplemented with human serum from young (YS) or old (OS) donors. There was a notable age-related decline in the number of MSCs per millilitre of BM aspirate revealed by the CFU-F assay (r = −0.527, p < 0.0001) or flow cytometry (r = −0.307, p = 0.0116). Compared to young donors (19-40 years old), colony IDs were significantly lower in older donors (61-89 years old), particularly for smaller-sized colonies (42% lower, p < 0.01). When cultured in media supplemented with OS, young and old donor MSCs formed colonies with lower IDs, by 21%, p < 0.0001, and 27%, p < 0.05, respectively, indicating the formation of smaller sparser colonies. No significant differences in the expression of selected adipogenic, osteogenic, stromal, and bone remodelling genes as well as CD295, CD146, CD106, and connexin 43 surface molecules were found in sorted CD45^lowCD271⁺ MSCs from young and old donors (n = 8 donors each). Altogether, these results show similar trends for age-related decline in BM MSC numbers measured by the CFU-F assay and flow cytometry and reveal age-related effects of human serum on MSC colony formation. No significant differences in selected gene expression in uncultured CD45^lowCD271⁺ MSCs suggest that old donor MSCs may not be inferior in regard to their multipotential functions. Due to large donor-to-donor variation in all donor groups, our data indicate that an individual's chronological age is not a reliable predictor of their MSC number or potency.

Association between human T cell leukemia virus 1 (HTLV-1) infection and advanced periodontitis in relation to hematopoietic activity among elderly participants: a cross-sectional study

BACKGROUND

We reported that human T cell leukemia virus 1 (HTLV-1) infection is positively associated with atherosclerosis. Recent evidence has revealed a close association of periodontitis with atherosclerosis, endothelial dysfunction, and disruption of the microcirculation. However, the association between HTLV-1 and advanced periodontitis has not been investigated to date. Since hematopoietic activity is closely linked to endothelial maintenance activity and is known to decline with age, we hypothesized that the state of hematopoietic activity influenced the association between HTLV-1 and advanced periodontitis in elderly participants.

METHODS

A cross-sectional study was performed including 822 elderly participants aged 60-99 years who participated in a dental health check-up. Advanced periodontitis was defined as a periodontal pocket ≥ 6.0 mm. Participants were classified as having low or high hematopoietic activity according to the median values of reticulocytes.

RESULTS

HTLV-1 infection was positively related to advanced periodontitis among participants with lower hematopoietic activity (lower reticulocyte count), but not among participants with higher hematopoietic activity (higher reticulocyte count). The adjusted odds ratio (95% confidence interval) considering potential confounding factors was 1.92 (1.05-3.49) for participants with a lower reticulocyte count and 0.69 (0.35-1.36) for participants with a higher reticulocyte count.

CONCLUSIONS

Among elderly participants, the association between HTLV-1 infection and advanced periodontitis is influenced by hematopoietic activity. Since hematopoietic activity is associated with endothelial maintenance, these findings provide an efficient tool for clarifying the underlying mechanism of the progression of periodontitis among elderly participants.

Reticulocyte levels have an ambivalent association with hypertension and atherosclerosis in the elderly: a cross-sectional study

Purpose: Age-related reduction in bone marrow activity has been shown to cause anemia, and hypertension and endothelial dysfunction (atherosclerosis) are age-related diseases. However, recent studies have revealed a close association between bone marrow activity and endothelial maintenance. This study aimed to determine the association between elevated reticulocyte levels in conjunction with vigorous bone marrow activity and hypertension and atherosclerosis among the elderly.

Study population and Methods: To determine the associations between reticulocyte levels and hypertension and atherosclerosis, we conducted a cross-sectional study of 2,098 elderly Japanese individuals, aged between 60 and 89 years, who had participated in an annual health check-up in 2014.

Results: Of the total study population, 1,348 individuals were diagnosed with hypertension (systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg and/or having used antihypertensive medication), and 393 were diagnosed with atherosclerosis (carotid intima-media thickness ≥1.1 mm). Reticulocyte levels were found to be significantly positively associated with hypertension and inversely associated with atherosclerosis. Cardiovascular risk factor-adjusted odds ratios and 95% confidence intervals for hypertension and atherosclerosis, when raised incrementally by 1 standard deviation to determine reticulocyte levels (5.5×10⁴ cells/μL for men and 5.0×10⁴ cells/μL for women), were 1.12 (1.01, 1.25) and 0.83 (0.72, 0.94), respectively.

Conclusion: Along with established cardiovascular risk factors, reticulocyte levels in elderly Japanese individuals were found to be positively associated with hypertension and inversely associated with atherosclerosis. This finding may help clarify the background mechanisms concerning the association between bone marrow activity and vascular remodeling.

Bone marrow mesenchymal stem cells: Aging and tissue engineering applications to enhance bone healing

Bone has well documented natural healing capacity that normally is sufficient to repair fractures and other common injuries. However, the properties of bone change throughout life, and aging is accompanied by increased incidence of bone diseases and compromised fracture healing capacity, which necessitate effective therapies capable of enhancing bone regeneration. The therapeutic potential of adult mesenchymal stem cells (MSCs) for bone repair has been long proposed and examined. Actions of MSCs may include direct differentiation to become bone cells, attraction and recruitment of other cells, or creation of a regenerative environment via production of trophic growth factors. With systemic aging, MSCs also undergo functional decline, which has been well investigated in a number of recent studies. In this review, we first describe the changes in MSCs during aging and discuss how these alterations can affect bone regeneration. We next review current research findings on bone tissue engineering, which is considered a promising and viable therapeutic solution for structural and functional restoration of bone. In particular, the importance of MSCs and bioscaffolds is highlighted. Finally, potential approaches for the prevention of MSC aging and the rejuvenation of aged MSC are discussed.

Bionic cartilage acellular matrix microspheres as a scaffold for engineering cartilage

Bionic cartilage acellular matrix microspheres (BCAMMs) made from decelluarized bionic cartilage microspheres (BCMs).

Exposure of the Bone Marrow Microenvironment to Simulated Solar and Galactic Cosmic Radiation Induces Biological Bystander Effects on Human Hematopoiesis

The stem cell compartment of the hematopoietic system constitutes one of the most radiosensitive tissues of the body and leukemias represent one of the most frequent radiogenic cancers with short latency periods. As such, leukemias may pose a particular threat to astronauts during prolonged space missions. Control of hematopoiesis is tightly governed by a specialized bone marrow (BM) microenvironment/niche. As such, any environmental insult that damages cells of this niche would be expected to produce pronounced effects on the types and functionality of hematopoietic/immune cells generated. We recently reported that direct exposure of human hematopoietic stem cells (HSC) to simulated solar energetic particle (SEP) and galactic cosmic ray (GCR) radiation dramatically altered the differentiative potential of these cells, and that simulated GCR exposures can directly induce DNA damage and mutations within human HSC, which led to leukemic transformation when these cells repopulated murine recipients. In this study, we performed the first in-depth examination to define changes that occur in mesenchymal stem cells present in the human BM niche following exposure to accelerated protons and iron ions and assess the impact these changes have upon human hematopoiesis. Our data provide compelling evidence that simulated SEP/GCR exposures can also contribute to defective hematopoiesis/immunity through so-called "biological bystander effects" by damaging the stromal cells that comprise the human marrow microenvironment, thereby altering their ability to support normal hematopoiesis.

Height indicates hematopoietic capacity in elderly Japanese men

Previously, we reported that height is an indicator of the capacity of vascular repair in elderly men, especially hypertensive men. On the other hand, hemoglobin could act as a possible biochemical index of hypertension-induced vascular damage. However, no studies have clarified the correlation between height and hematopoietic activity. We conducted a cross-sectional study of 249 men aged 65-69 undergoing a general health check-up. Reticulocyte was used to evaluate hematopoietic activity. Because hemoglobin concentration should influence hematopoietic activity, analyses stratified by hemoglobin level were performed. Independent of known cardiovascular risk factors and other hematological parameters (white blood cell count), a significant positive correlation was seen between height and reticulocytes for total subjects and subjects with a high hemoglobin concentration (≥14.5 g/dL), but not in subjects with a low hemoglobin concentration (<14.5 g/dL). The standardized parameter estimates (β) were β=0.18, p=0.003 for total subjects, β=0.28, p=0.001 for subjects with a high hemoglobin concentration, and β=0.03, p=0.717 for subjects with low hemoglobin. Independently, height is significantly positively correlated with reticulocyte in elderly Japanese men, particularly in men with a high hemoglobin concentration. These results indicate that subjects with a short stature might have lower hematopoietic capacity than those with a high stature.

Handgrip strength and subclinical carotid atherosclerosis in relation to platelet levels among hypertensive elderly Japanese

Age-related disruption of microvascular endothelium exacerbates hypertension and sarcopenia; and atherosclerosis is a well-known biological response to vascular endothelial injury. Therefore, prevalence of atherosclerosis among hypertensive elderly subjects may partly indicate the presence of an appropriate response to endothelial injury. We conducted a cross-sectional study of 795 elderly hypertensive Japanese subjects aged 60-89 years. Since platelet level is an indicator of vascular repair activity, subjects were stratified by platelet counts. No significant association between handgrip strength and subclinical carotid atherosclerosis (carotid intima-media thickness (CIMT) ≥1.1mm) was observed for subjects with lower platelet counts, while a significant positive association was observed for subjects with higher platelets. Adjusted odds and 95% confidence intervals of subclinical carotid atherosclerosis for 1 standard deviation increments in handgrip strength were 0.86 (0.61, 1.22) for subjects with lower platelets and 1.82 (1.26, 2.64) for subjects with higher platelets. A positive association between handgrip strength and subclinical carotid atherosclerosis exists in hypertensive elderly subjects with higher, but not lower, platelet counts. These results lead us to speculate that subjects with a beneficial influence on prevention of sarcopenia (maintenance of handgrip strength) may possess the capacity of active endothelial repair that causes atherosclerosis.

Possible mechanism underlying the association between higher hemoglobin level and hypertension in older Japanese men

AIM

Hemoglobin is reported to be positively associated with hypertension. However, the underlying mechanism of this association is unknown. Recently, bone marrow-derived CD34-positive cells have been reported to play an important role in endothelial repair in conjunction with platelets. As the association between hypertension and endothelial dysfunction is bidirectional, the influence of endothelial repair also might strongly influence the association between hemoglobin and hypertension.

METHODS

To clarify the clinical importance of the hematological parameter on endothelial maintenance in older men, we carried out a cross-sectional study of 222 Japanese men aged 60-69 years undergoing a general health checkup.

RESULTS

For participants with a lower platelet count (≤21.0/μL), hemoglobin was significantly positively associated with hypertension, but not for participants with a higher platelet count (>21.0/μL). The classical cardiovascular risk factor adjusted odds ratio of hypertension for 1-standard deviation increment of hemoglobin (1.0 g/dL) was 2.09 (95% CI: 1.26, 3.48) for participants with a lower platelet count, and 1.07 (95% CI: 0.68, 1.67) for participants with a higher platelet count. We also found that although there was no significant correlation between hemoglobin and circulating CD34-positive cells for participants with a lower platelet count (β = -0.06, P = 0.603), a significant positive correlation was seen for participants with a higher platelet count (β = 0.29, P = 0.004).

CONCLUSIONS

The positive association between hemoglobin and hypertension was limited to participants with a lower platelet count as a result of insufficient endothelial repair. These results represent an efficient tool for clarifying the mechanism of endothelial maintenance that correlates with hypertension. Geriatr Gerontol Int 2017; 17: 2586-2592.

Height is an indicator of vascular maintenance capacity in older men

AIM

Bone-derived circulating CD34-positive cells are reported to play an important role in vascular maintenance. Additionally, height might influence age-related hematopoietic bone marrow decline, as it positively correlates with total bone marrow volume. As hypertension should mask the beneficial effects of circulating CD34-positive cells, hypertension status should account for this correlation. The present study aimed to clarify the clinical importance of height on vascular maintenance in older Japanese men.

METHODS

We carried out a cross-sectional study of 343 older men aged 65-69 years who underwent a general health checkup from 2013 to 2015.

RESULTS

Independent of known cardiovascular risk factors, height was found to be slightly, but significantly, positively correlated with the log number of circulating CD34-positive cells in systolic, but not non-systolic, hypertensive men. Multilinear regression analysis showed a parameter estimate (B) and standardized parameter estimate (β) of 3.23 × 10^-2 , 0.28 (P = 0.003) for systolic hypertensive men and -0.49 × 10^-2 , -0.04 (P = 0.495) for non-systolic hypertensive men.

CONCLUSIONS

Height positively correlates with circulating CD34-positive cells in systolic, but not non-systolic, hypertensive men. As the beneficial effects of circulating CD34-positive cells on endothelial repair might be masked by hypertension where the production of CD34-positive cells is stimulated by hypertension-induced vascular damage, among individuals with systolic hypertension, circulating CD34-positive cells should indicate the limits of endothelial repair. Therefore, height might indicate the capacity for adequate vascular maintenance in older men. Geriatr Gerontol Int 2017; 17: 1729-1736.

Association between circulating CD34-positive cells and serum alkaline phosphatase in relation to body mass index for elderly Japanese men

Background

Recent studies have confirmed an association between bone metabolism and vascular homeostasis. However, no study has examined the relationship between serum alkaline phosphatase (ALP) (a marker of bone metabolism) and circulating immature cell such as CD34-positive cells (a marker of vascular homeostasis).

Methods

We conducted a cross-sectional study of this association in 272 elderly Japanese men (60–79 years). Because low body mass index (BMI) status is a known characteristic of Japanese with a high incidence rate of stroke, we used a stratified analysis based on BMI.

Results

Multivariable linear regression analysis adjusted for confounding factors showed a significant correlation between serum ALP and the number of circulating CD34-positive cells, especially for participants with low BMI (<23 kg/m²). The parameter estimates (β) and 95 % confidence intervals (CI) for one standard deviation increments in serum ALP levels (62 IU/L) for the circulating CD34-positive cell count were β = 0.25 (0.04, 0.45) for total subjects, β = 0.45 (0.16, 0.75) for participants with low BMI (<23 kg/m²), and β = 0.04 (−0.25, 0.34) for participants with high BMI (≥23 kg/m²).

Conclusion

Serum ALP correlates positively with circulating CD34-positive cells among a general population of elderly Japanese men, especially those with low BMI (<23 kg/m²). These findings suggest that serum ALP levels may constitute an efficient tool for estimating the risk of insufficient vascular homeostasis, especially for participants with relatively few classical cardiovascular risk factors.

[Hematopoietic stem cell exhaustion and advanced glycation end-products in the unexplained anemia of the elderly]

INTRODUCTION

More than 10% of the aged 65 years and over in the western world suffers anemia and in one third of them the cause of the anemia remains obscure. The unexplained anemia of the elderly (UAE) is considered an exclusion diagnosis, without the existence of a clear consensus to its clinical or experimental approach. There is an association between aging and anemia in studies performed in animals and in humans.

OBJECTIVES

To determine if there is evidence in the literature that supports hematopoietic stem cells (HSC) exhaustion and the advanced glycation end-products (AGE's) as a cause of UAE.

METHOD

A total of 32 combined texts (28 for HSC exhaustion and 4 for AGEs) were selected after an intensive review. Conclusions were associated with causes and effects of the HSC exhaustion and circulating AGE's over aging and anemia.

RESULTS

Only three works try to establish an association between UAE and HSC exhaustion, two of them disagreed in their conclusions, with the third one differing in the type of study. There is a relationship between anemia and AGEs increase and accumulation.

CONCLUSIONS

There is evidence in the literature that links the aging molecular and cellular mechanisms with the HSC exhaustion and the increase of AGE's. Furthermore; there is some evidence that both conditions determine the emergence of anemia associated with age in animals and in humans. There is little evidence in the literature to clarify the relationship between aging and UAE.

Height and drinking status in relation to risk of anemia in rural adult healthy Japanese men: the Nagasaki Islands study

BACKGROUND

Several studies have reported that height is inversely associated with risk of cardiovascular disease but positively associated with cancer risk. On the other hand, evidence has been accumulating that anemia reflects poor health and increased vulnerability to poor outcomes in older persons. Moreover, alcohol consumption has also been reported to be associated with mortality. However, no studies have reported on a possible association between height and risk of anemia in relation to drinking status.

METHODS

We conducted a cross-sectional study of 1287 men aged 40-89 years undergoing general health check-ups.

RESULTS

Independent from classic cardiovascular risk factors, we found a significant inverse association between height and anemia for non-drinkers and a J-shaped association for drinkers. The multivariable odds ratio (ORs) of an increment of 1 SD (standard deviation) in height (6.68 cm) for anemia for non-drinkers was 0.59 (0.45-0.77). For drinkers, with the second quartile of height (Q2) as the reference group, the multivariable OR of anemia was 2.68(0.90-7.96) (p = 0.075) for the lowest height quartile (Q1), 2.73(0.92-8.08) for the third quartile (Q3) and 4.82(1.65-14.10) for the highest quartile (Q4) (p = 0.004).

CONCLUSION

Height was found to be associated with anemia for rural Japanese men and drinking status is likely to affect those associations.

Application of Nanoscaffolds in Mesenchymal Stem Cell-Based Therapy

Regenerative medicine is an alternative solution for organ transplantation. Stem cells and nanoscaffolds are two essential components in regenerative medicine. Mesenchymal stem cells (MSCs) are considered as primary adult stem cells with high proliferation capacity, wide differentiation potential, and immunosuppression properties which make them unique for regenerative medicine and cell therapy. Scaffolds are engineered nanofibers that provide suitable microenvironment for cell signalling which has a great influence on cell proliferation, differentiation, and biology. Recently, application of scaffolds and MSCs is being utilized in obtaining more homogenous population of MSCs with higher cell proliferation rate and greater differentiation potential, which are crucial factors in regenerative medicine. In this review, the definition, biology, source, characterization, and isolation of MSCs and current report of application of nanofibers in regenerative medicine in different lesions are discussed.

Stro-1-positive BMSCs predict postoperative periprosthetic bone mineral density outcomes in uncemented total hip arthroplasty patients

Background

Bone marrow cell profiles are variable after total hip arthroplasty (THA), including variable levels of Stro-1⁺ and bone morphogenetic protein receptor (BMPRs)⁺ cells. We investigated the impact of bone marrow cell profiles on changes in periprosthetic bone mineral density (BMD) in uncemented THA patients.

Material/Methods

Bone marrow aspirates were collected from the metaphyseal region of discarded femoral heads from 24 consecutive THA patients (12 men and 12 women; mean age 66.7±11.0 years; range 52–87 years) treated from March 2009 to March 2011 at a single facility. Perioperative proportions of Stro-1⁺ and BMPR⁺ cells in femoral heads were assessed by flow cytometry. Follow-up examined the proximal femur Gruen zones R1 and R7 at 1 week and at 3, 6, and 12 months after THA, using dual-energy X-ray absorptiometry. Associations between BMD loss and age, gender, BMPRs⁺, and Stro-1⁺ were analyzed.

Results

At 3 months, R1 and R7 BMD decreased by 4.4% and 6.4%, respectively (P<0.05). At 12 months, the overall BMD decreases in R1 and R7 were 10.2% and 1%, respectively (P<0.05). Higher Stro-1⁺ cells proportion predicted R7 BMD increases at all time points (P<0.05) and R1 BMD increases at 6 and 12 months (P<0.05). BMPR1a⁺ proportion was associated with BMD increases at 6 months in the R1 region. BMPR2⁺ was not significantly associated with BMD (P>0.05).

Conclusions

Elevated Stro-1⁺ bone marrow cell profile may be a useful prognostic indicator for uncemented THA patients.

Changes in the frequencies of human hematopoietic stem and progenitor cells with age and site

This study enumerated CD45(hi)/CD34(+) and CD45(hi)/CD133(+) human hematopoietic stem cells (HSCs) and progenitor granulocyte-macrophage colony forming cells (GM-CFCs) in blood and trochanteric and femoral bone marrow in 233 individuals. Stem cell frequencies were determined with multiparameter flow cytometry and using an internal control to determine the intrinsic variance of the assays. Progenitor cell frequency was determined using a standard colony assay technique. The frequency of outliers from undetermined methodological causes was highest for blood, but less than 5% for all values. The frequency of CD45(hi)/CD133(+) cells correlated highly with the frequency of CD45(hi)/CD34(+) cells in trochanteric and femoral bone marrow. The frequency of these HSC populations in trochanteric and femoral bone marrow rose significantly with age. In contrast, there was no significant trend of either of these cell populations with age in the blood. Trochanteric marrow progenitor GM-CFCs showed no significant trends with age, but femoral marrow GM-CFCs trended downward with age, potentially because of the reported conversion of red marrow at this site to fat with age. Hematopoietic stem and progenitor cells exhibited changes in frequencies with age that differed between blood and bone marrow. We previously reported that side population (SP) multipotential HSC, which includes the precursors of CD45(hi)/CD133(+) and CD45(hi)/CD34(+), decline with age. Potentially the increases in stem cell frequencies in the intermediate compartment between SP and GM progenitor cells observed in this study represent a compensatory increase for the loss of more potent members of the HSC hierarchy.

SP/drug efflux functionality of hematopoietic progenitors is controlled by mesenchymal niche through VLA-4/CD44 axis

Hematopoiesis is orchestrated by interactions between hematopoietic stem/progenitor cells (HSPCs) and stromal cells within bone marrow (BM) niches. Side population (SP) functionality is a major characteristic of HSPCs related to quiescence and resistance to drugs and environmental stresses. At steady state, SP cells are mainly present in the BM and are mostly absent from the circulation except in stress conditions, raising the hypothesis of the versatility of the SP functionality. However, the mechanism of SP phenotype regulation is unclear. Here we show for the first time that the SP functionality can be induced in lin(-) cells from unmobilized peripheral blood after nesting on mesenchymal stromal cells (MSCs). This MSC-induced SP fraction contains HSPCs as demonstrated by their (i) CD34(+) cell percentage, (ii) quiescent status, (iii) in vitro proliferative and clonogenic potential, (iv) engraftment in NSG (NOD SCID gamma chain) mice and (v) stemness gene expression profile. We demonstrate that SP phenotype acquisition/reactivation by circulating lin(-) cells is dependent on interactions with MSCs through VLA-4/α4β1-integrin and CD44. A similar integrin-dependent mechanism of SP phenotype acquisition in acute myeloid leukemia circulating blasts suggests an extrinsic regulation of ATP-binding cassette-transporter activity that could be of importance for a better understanding of adhesion-mediated chemoresistance mechanisms.

Changes of number of cells expressing proliferation and progenitor cell markers with age in rabbit intervertebral discs

Basic knowledge about the normal regeneration process within the intervertebral disc (IVD) is important to the understanding of the underlying biology. The presence of progenitor and stem cells in IVD has been verified. However, changes of number of progenitor and stem cells with age are still unknown. In this study, changes of cell proliferation and progenitor cell markers with age in IVD cells from rabbits of two different ages were investigated using flow cytometry, immunohistochemistry, real-time polymerase chain reaction, and western blot analysis. Proliferating cell nuclear antigen (PCNA) was chosen as a marker for proliferation, and Notch1, Jagged1, C-KIT, CD166 were chosen as stem/progenitor cell markers. Cell cycle analysis showed that cell number in the G2/M phase of the young rabbits was significantly higher than that of mature rabbits. Immunohistochemical staining demonstrated the expression of PCNA, C-KIT, CD166, Notch1, and Jagged1 in both young and mature annulus fibrosus (AF). Protein expressions of these cell markers in the young rabbits were all significantly higher than those in the mature rabbits. The expression levels of PCNA, CD166, C-KIT, Jagged1 were significantly higher in the AF, and PCNA, C-KIT in the nucleus pulposus from young rabbits than those from the mature rabbits. These findings demonstrated that both proliferation and progenitor cells exist in rabbit IVDs and the number of cells expressing proliferation and progenitor cell markers decreases with age in the rabbit IVD cells. Methods that are designed to maintain the endogenous progenitor cells and stimulate their proliferation could be successful in preventing or inhibiting degenerative disc disease.

Kidney transplantation and the ageing immune system

The world population is rapidly growing and ageing at a pace that is projected to continue for at least three decades. This shift towards an older populace has invariably increased the number of individuals with diseases related to ageing, such as chronic kidney disease. The increase in chronic kidney disease is associated with a growing number of elderly patients receiving kidney transplants. Understanding how the immune system changes with increasing age will help to define the risks of rejection and infection in the elderly population and will focus attention on the need for individualized immunosuppression for patients in this age group. This Review addresses what is currently known about ageing and the immune system, highlighting age-related changes that affect the outcome of transplantation in elderly individuals. The need for new strategies to improve outcomes in this growing population of elderly renal transplant recipients is also emphasized.

In situ guided tissue regeneration in musculoskeletal diseases and aging : Implementing pathology into tailored tissue engineering strategies

In situ guided tissue regeneration, also addressed as in situ tissue engineering or endogenous regeneration, has a great potential for population-wide "minimal invasive" applications. During the last two decades, tissue engineering has been developed with remarkable in vitro and preclinical success but still the number of applications in clinical routine is extremely small. Moreover, the vision of population-wide applications of ex vivo tissue engineered constructs based on cells, growth and differentiation factors and scaffolds, must probably be deemed unrealistic for economic and regulation-related issues. Hence, the progress made in this respect will be mostly applicable to a fraction of post-traumatic or post-surgery situations such as big tissue defects due to tumor manifestation. Minimally invasive procedures would probably qualify for a broader application and ideally would only require off the shelf standardized products without cells. Such products should mimic the microenvironment of regenerating tissues and make use of the endogenous tissue regeneration capacities. Functionally, the chemotaxis of regenerative cells, their amplification as a transient amplifying pool and their concerted differentiation and remodeling should be addressed. This is especially important because the main target populations for such applications are the elderly and diseased. The quality of regenerative cells is impaired in such organisms and high levels of inhibitors also interfere with regeneration and healing. In metabolic bone diseases like osteoporosis, it is already known that antagonists for inhibitors such as activin and sclerostin enhance bone formation. Implementing such strategies into applications for in situ guided tissue regeneration should greatly enhance the efficacy of tailored procedures in the future.

Characterization of spontaneous bone marrow recovery after sublethal total body irradiation: importance of the osteoblastic/adipocytic balance

Many studies have already examined the hematopoietic recovery after irradiation but paid with very little attention to the bone marrow microenvironment. Nonetheless previous studies in a murine model of reversible radio-induced bone marrow aplasia have shown a significant increase in alkaline phosphatase activity (ALP) prior to hematopoietic regeneration. This increase in ALP activity was not due to cell proliferation but could be attributed to modifications of the properties of mesenchymal stem cells (MSC). We thus undertook a study to assess the kinetics of the evolution of MSC correlated to their hematopoietic supportive capacities in mice treated with sub lethal total body irradiation. In our study, colony-forming units – fibroblasts (CFU-Fs) assay showed a significant MSC rate increase in irradiated bone marrows. CFU-Fs colonies still possessed differentiation capacities of MSC but colonies from mice sacrificed 3 days after irradiation displayed high rates of ALP activity and a transient increase in osteoblastic markers expression while pparγ and neuropilin-1 decreased. Hematopoietic supportive capacities of CFU-Fs were also modified: as compared to controls, irradiated CFU-Fs significantly increased the proliferation rate of hematopoietic precursors and accelerated the differentiation toward the granulocytic lineage. Our data provide the first evidence of the key role exerted by the balance between osteoblasts and adipocytes in spontaneous bone marrow regeneration. First, (pre)osteoblast differentiation from MSC stimulated hematopoietic precursor's proliferation and granulopoietic regeneration. Then, in a second time (pre)osteoblasts progressively disappeared in favour of adipocytic cells which down regulated the proliferation and granulocytic differentiation and then contributed to a return to pre-irradiation conditions.

Impacts of age and gender on bone marrow profiles of BMP7, BMPRs and Stro-1⁺ cells in patients with total hip replacement

PURPOSE

A successful osseointegration relies on the interplay of implant surface and surrounding bone marrow cells. This study was undertaken to investigate the impact of age and gender on the bone marrow composition.

METHODS

Bone marrow aspirates were obtained from the discarded metaphysis region of the femoral head in 24 patients with total hip replacement. Flow cytometry was used to measure the expression of Stro-1(+) cells and BMP receptors (BMPRs)-expressing cells. ELISA was used to measure bone marrow aspirate bone morphology protein7 (BMP7) concentration.

RESULTS

Our data demonstrates that there are diverse bone marrow profiles (Stro-1(+) cell and BMPRs(+) cells). There are no differences of Stro-1(+) cells, BMPRs(+) cells, and BMP7 concentration between male and female patients. Though there are slight increases in the number of Stro-1(+) cells and BMPRs(+) cells in younger patients (<70 years old) than those of old patients (≥ 70 years old), the difference is not statistically significant. However, we found a close association between the Stro-1(+) cells, BMPR1a cells and BMP7 concentration. In addition, a correlation exists between the number of Stro-1(+) cells and BMIs of these patients.

CONCLUSION

Our data suggests that the age and gender of THR patients have little impact on their bone marrow osteogenic potential. The significance of the number of the Stro-1(+) with BMPRs expression on the implant fixation and osseointegration warrants further investigation.

Changes in human bone marrow fat content associated with changes in hematopoietic stem cell numbers and cytokine levels with aging

Hematological deficiencies increase with aging, including anemias, reduced responses to hematopoietic stress and myelodysplasias. This investigation tested the hypothesis that increased bone marrow (BM) fat content in humans with age was associated with decreased numbers of side population (SP) hematopoietic stem cells, and this decrease correlated with changes in cytokine levels. BM was obtained from the femoral head and trochanteric region of the femur removed at surgery for total hip replacement (N = 100 subjects). In addition, BM from cadavers (N = 36), with no evidence of hip disease, was evaluated for fat content. Whole trabecular marrow samples were ground in a sterile mortar and pestle, and cellularity and lipid content determined. Marrow cells were stained with Hoechst dye and SP profiles were acquired. Plasma levels of insulin-like growth factor (IGF)-1, stromal-derived factor (SDF)-1 and interleukin (IL)-6 were measured using ELISA. Fat content in the BM of human subjects and cadavers increased with age. The numbers of SP stem cells in BM as well as plasma IGF-1 and SDF-1 levels decreased in correlation with increased BM fat. IL-6 had no relationship to changes in marrow fat. These data suggest that increased BM fat may be associated with a decreased number of SP stem cells and IGF-1 and SDF-1 levels with aging. These data further raise a more general question as to the role of adipose cells in the regulation of tissue stem cells.

Mesenchymal stem cells: from experiment to clinic

There is currently much interest in adult mesenchymal stem cells (MSCs) and their ability to differentiate into other cell types, and to partake in the anatomy and physiology of remote organs. It is now clear these cells may be purified from several organs in the body besides bone marrow. MSCs take part in wound healing by contributing to myofibroblast and possibly fibroblast populations, and may be involved in epithelial tissue regeneration in certain organs, although this remains more controversial. In this review, we examine the ability of MSCs to modulate liver, kidney, heart and intestinal repair, and we update their opposing qualities of being less immunogenic and therefore tolerated in a transplant situation, yet being able to contribute to xenograft models of human tumour formation in other contexts. However, such observations have not been replicated in the clinic. Recent studies showing the clinical safety of MSC in several pathologies are discussed. The possible opposing powers of MSC need careful understanding and control if their clinical potential is to be realised with long-term safety for patients.