The effects of platelet-rich plasma on the osteogenic induction of bone marrow mesenchymal stem cells

Biofunctionalized hydrogel composed of genipin-crosslinked gelatin/hyaluronic acid incorporated with lyophilized platelet-rich fibrin for segmental bone defect repair

Segmental bone defects can arise from trauma, infection, metabolic bone disorders, or tumor removal. Hydrogels have gained attention in the field of bone regeneration due to their unique hydrophilic properties and the ability to customize their physical and chemical characteristics to serve as scaffolds and carriers for growth factors. However, the limited mechanical strength of hydrogels and the rapid release of active substances have hindered their clinical utility and therapeutic effectiveness. With ongoing advancements in material science, the development of injectable and biofunctionalized hydrogels holds great promise for addressing the challenges associated with segmental bone defects. In this study, we incorporated lyophilized platelet-rich fibrin (LPRF), which contains a multitude of growth factors, into a genipin-crosslinked gelatin/hyaluronic acid (GLT/HA-0.5 % GP) hydrogel to create an injectable and biofunctionalized composite material. Our findings demonstrate that this biofunctionalized hydrogel possesses optimal attributes for bone tissue engineering. Furthermore, results obtained from rabbit model with segmental tibial bone defects, indicate that the treatment with this biofunctionalized hydrogel resulted in increased new bone formation, as confirmed by imaging and histological analysis. From a translational perspective, this biofunctionalized hydrogel provides innovative and bioinspired capabilities that have the potential to enhance bone repair and regeneration in future clinical applications.

Core decompression combined with platelet-rich plasma-augmented bone grafting for femur head necrosis: a systematic review and meta-analysis

BACKGROUND

The clinical potential of biologic augmentation in core decompression and bone grafting for femoral head necrosis is widely acknowledged, with platelet-rich plasma (PRP) being a frequently employed biologic adjunct. However, its clinical application is not standardized, and high-level evidence is lacking. This study aimed to evaluate the efficacy and safety of core decompression and bone grafting combined with PRP for femur head necrosis.

METHODS

Several databases were systematically retrieved for randomized controlled trials comparing core decompression and bone grafting combined with or without PRP. A systematic review and meta-analysis were conducted following the PRISMA 2020 and AMSTAR 2 guidelines. The study is registered with PROSPERO under the code CRD42022361007, and it is also listed in the research registry under the identification number reviewregistry1537.

RESULTS

Eleven studies with 642 participants (742 hips) were included. The pooled estimates revealed that when core decompression and bone grafting were combined with PRP, the Harris hip score (mean difference: 7.98; 95% CI: 5.77-10.20; P <0.001), visual analog scale (SMD: -0.68; 95% CI: -0.96 - -0.40; P <0.001) and the pain component of Harris hip score (SMD: 8.4; 95% CI: 4.12-12.68; P <0.001), and reduction of radiographic progression [risk ratio (RR): 0.40; 95% CI: 0.27-0.59; P <0.001] were superior to core decompression and bone grafting alone. Fewer patients with treatment failure (RR: 0.27; 95% CI: 0.14-0.52; P <0.001) and higher good-to-excellent results (RR: 1.48; 95% CI: 1.17-1.86; P <0.001) were observed in treatment groups than control groups. Meanwhile, the pooled analysis substantiated the superior safety profile of PRP (RR: 0.29; 95% CI: 0.11-0.77; P =0.01).

CONCLUSIONS

The combination of core decompression and bone grafting with PRP is superior to the approach without PRP, demonstrating enhanced effectiveness in terms of function, pain relief, and radiographic progression. Additionally, it results in lower rates of treatment failure and adverse events. However, further high-quality RCTs are needed to evaluate their effectiveness due to methodological and implementation limitations observed in the existing evidence.

Advances with Platelet-Rich Plasma for Bone Healing

Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.

Association between platelet, white blood cell count, platelet to white blood cell ratio and sarcopenia in community-dwelling older adults: focus on Bushehr Elderly Health (BEH) program

BACKGROUND

Sarcopenia is a progressive age-related skeletal muscle disorder associated with harmful impacts on health. The present study aimed to investigate the relation between sarcopenia, platelet (PLT), white blood cell (WBC), and PLT to WBC ratio (PWR) due to the importance of early sarcopenia diagnosis.

METHODS

This cross-sectional study was conducted based on the second stage of the Bushehr Elderly Health (BEH) Program. Sarcopenia was defined based on the revised edition of the European Working Group on Sarcopenia in Older People (EWGSOP2) in accordance with the Iranian cut-off point. Univariate and adjusted multivariate logistic regression and linear regression were used to evaluate the associations.

RESULTS

The prevalence of sarcopenia among participants was 35.73%. PLT count and PWR were statistically higher in severe sarcopenic participants, while no differences were seen in WBC. In crude analysis, sarcopenia was not associated with quartiles of PLT, WBC, and PWR, while after adjusting for age, marital status, and sex, the association was seen in the fourth quartile of PLT and PWR [OR (95%CI) = 1.40 (1.08 to 1.81), p-value = 0.009 for PLT; OR (95%CI) =1.55 (1.20 to 2.00), p-value =0.001 for PWR]. This association remained significant in the fully adjusted model [OR (95%CI) =1.82 (1.20 to 2.78), p-value =0.005 for PLT; OR (95%CI) =1.57 (1.03 to 2.40), p-value =0.035 for PWR]. Among sarcopenia parameters, PLT count was more likely to be associated with handgrip strength and muscle mass. After stratifying the participants by gender, sarcopenia parameters were no longer statistically significant in men.

CONCLUSION

This study showed that PLT and PWR were associated with sarcopenia after considering confounding factors, while this association was not seen in WBC. Moreover, results showed that gender had an important impact on sarcopenia parameters.

Knee Intraosseous Injections: A Systematic Review of Clinical Evidence of Different Treatment Alternatives

OBJECTIVE

To systematically review the available clinical evidence regarding the safety and efficacy of knee intraosseous injections for the treatment of bone marrow lesions in patients affected by knee osteoarthritis.

DESIGN

A literature search was carried out on PubMed, Embase, and Google Scholar databases in January 2020. The following inclusion criteria were adopted: (1) studies of any level of evidence, dealing with subchondral injection of bone substitute materials and/or biologic agents; (2) studies with minimum 5 patients treated; and (3) studies with at least 6 months' follow-up evaluation. All relevant data concerning clinical outcomes, adverse events, and rate of conversion to arthroplasty were extracted.

RESULTS

A total of 12 studies were identified: 7 dealt with calcium phosphate administration, 3 with platelet-rich plasma, and 2 with bone marrow concentrate injection. Only 2 studies were randomized controlled trials, whereas 6 studies were prospective and the remaining 4 were retrospective. Studies included a total of 459 patients treated with intraosseous injections. Overall, only a few patients experienced adverse events and clinical improvement was documented in the majority of trial. The lack of any comparative evaluation versus subchondral drilling alone is the main limitation of the available evidence.

CONCLUSIONS

Knee intraosseous injections are a minimally invasive and safe procedure to address subchondral bone damage in osteoarthritic patients. They are able to provide beneficial effects at short-term evaluation. More high-quality evidence is needed to confirm their potential and to identify the best product to adopt in clinical practice.

Effects of porcine bone marrow-derived platelet-rich plasma on bone marrow-derived mesenchymal stem cells and endothelial progenitor cells

This study investigated the abundance of pro-regenerative growth factors in bone marrow-derived platelet-rich plasma (BM-PRP) and their effects on bone marrow-derived mesenchymal stem cells (BM-MSC) and bone marrow-derived endothelial progenitor cells (BM-EPC). Four 4-5 months-old domestic pigs were included, and each underwent bone marrow aspiration from its humerus bones and processed into bone marrow aspiration concentrate (BMAC) samples. The plasma and cellular portions of BMAC were subsequently separated and collected. The concentration of growth factors including BMP-2, PDGF-BB, TGF-β1 and VEGF in the plasma portion was measured and compared between BM-PRP and bone marrow-derived platelet-poor plasma (BM-PPP). It was found that platelet count was significantly higher in BM-PRP than in BM-PPP, but the concentration of above-mentioned growth factors was not significantly different between BM-PRP and BM-PPP. As most existing literature has indicated the regenerative potency of PRP, this study focused on assessing the effect of BM-PRP treatment on BM-MSC and BM-EPC proliferation, osteogenic differentiation and angiogenesis capacity by comparing samples with 2.5% BM-PRP treatment and samples without BM-PRP treatment (control). In response to BM-PRP treatment, the cellular doubling time increased with culturing time and was significantly shorter in the BM-PRP-treated samples than in control samples. For osteogenic differentiation, BM-PRP-treated BM-MSCs demonstrated a time-dependent increase in alkaline phosphatase (ALP) activity and expression levels of osteogenic differentiation markers. For the expression of angiogenic genes, none of the differences reached statistical significance despite a tendency of stronger expression at day 18 in BM-PRP-treated BM-EPCs. In conclusion, this in vitro study suggests that most BMP-2, PDGF-BB, TGF-β1 and VEGF-A contained in BM-PRP are not platelet-released and BM-PRP may have some stimulation (less than 1-fold) for MSC, EPC proliferation and MSC osteogenic differentiation.

Association between serum sodium level within normal range and handgrip strength in relation to hypertension status: a cross-sectional study

Serum sodium concentration within the normal range could act as an indicator of age-related changes such as decrease in muscle strength and impairment of capillary function. Since endothelial injury stimulates endothelial repair by enhancing CD34-positive cell production, the level of serum sodium may be inversely associated with that of circulating CD34-positive cells, thus indicating the degree of age-related endothelial injury. We conducted a cross-sectional study of 246 elderly Japanese men aged 60–69 years. Subjects were stratified by hypertension status because hypertension should act as a strong confounding factor for the analyses performed in this study. Serum sodium concentration was positively associated with handgrip strength in non-hypertensive subjects [standardized parameter estimate (β) = 0.29; p = 0.003], but not for hypertensive subjects (β = 0.01; p = 0.878), while it was inversely associated with circulating CD34-positive cell levels in non-hypertensive subjects [simple correlation coefficient (r) = − 0.28; p = 0.002] but not for hypertensive subjects (r = − 0.07; p = 0.454). For non-hypertensive elderly subjects, serum sodium concentration within the normal range is positively associated with handgrip strength and inversely associated with CD34-positive cells, thus partly indicating the degree of age-related endothelium injury. These associations could prove to be an efficient tool for clarifying the background mechanism governing the decrease in age-related muscle strength.

Tetrandrine Attenuates Cartilage Degeneration, Osteoclast Proliferation, and Macrophage Transformation through Inhibiting P65 Phosphorylation in Ovariectomy-induced Osteoporosis

BACKGROUND

Osteoporosis is a common metabolic bone disease with high prevalence. Tetrandrine (TET) suppressed osteoclastogenesis, while the roles of TET in osteoporosis regulation remained unclear. Thus, the study aimed to investigate the effect of TET on osteoporosis and the underlying mechanism.

METHODS

The osteoporosis rabbit model was established through anterior cruciate ligament transection (ACLT) and bilateral ovariectomy (OVX). The degeneration of articular cartilage was assessed using HE staining and Alcian blue staining. The liver and kidney tissue injury was determined using HE staining. The activity of osteoclasts was evaluated using Tartrate-resistant acid phosphatase (TRAP) staining. The changes in bone structural parameters were determined through measuring the BMD, BV/TV, Tb.Th, Tb.N, and Tb.Sp, and the serum levels of calcium and phosphorus. Macrophage polarization was determined using Flow cytometry.

RESULTS

The bone structural parameters including BMD, BV/TV, Tb.N, Tb.Th and Tb.Sp were changed in osteoporosis rabbit, which was reversed by TET. Besides, TET suppressed the increased serum levels of calcium and phosphorus in osteoporosis rabbit. Furthermore, TET inhibited the degeneration of articular cartilage and the activity of osteoclasts induced by osteoporosis. Moreover, TET inhibited the levels of MMP-9, PPAR-γ, RANKL, β-CTX and TRACP-5b, and increased the levels of OPG, ALP and osteocalcin (OC) in osteoporosis. Additionally, TET promoted macrophage transformation from M1 to M2 in osteoporotic and inhibited the production of IL-1β, TNF-α, and IL-6. TET also inhibited the p65 phosphorylation in osteoporosis. Besides, TET reversed RANKL-induced osteoclasts proliferation, p65 phosphorylation, and the expression changes of RANKL, Ki67, PPAR-γ, ALP, OPG.

CONCLUSION

TET attenuated bone structural parameters including BMD, BV/TV, Tb.N, Tb.Th and Tb.Sp, inhibited articular cartilage degeneration, promoted bone formation, inhibited the inflammatory response, and promoted macrophage transformation from M1 to M2 via NF-κB inactivation in osteoporosis. TET may be a promising drug for osteoporosis therapy.

ABBREVIATION

TET: Tetrandrine; ACLT: anterior cruciate ligament transection; OVX: ovariectomy; TRAP: Tartrate-resistant acid phosphatase; BMD: bone mineral density; BV/TV: Bone volume/total volume; Tb.Th: trabecular thickness; Tb.N: trabecular number; Tb.Sp: trabecular separation; MMP-9: Matrix metallopeptidase 9; PPAR-γ: Peroxisome proliferator-activated receptor gamma; RANKL: Receptor activator of nuclear factor kappa-B ligand; OPG: Osteoprotegerin; ALP: alkaline phosphatase; OC: osteocalcin; β-CTX: β isomer of C-terminal telopeptide of type Ⅰ collagen; TRACP-5b: Tartrate-resistant acid phosphatase 5b; TNF-α: tumor necrosis factor-α; IL-1β: interleukin-1β; IL-6: interleukin 6; NF-κB: Nuclear factor kappa B; PKC-α: Protein kinase C alpha; qRT-PCR: Quantitative real-time polymerase chain reaction.

Autogenous bone particles combined with platelet-rich plasma can stimulate bone regeneration in rabbits

Long-term bone defects are a key clinical problem. Autogenous bone graft remains the gold standard for the treatment of these defects; however, improving the osteogenic properties and reducing the amount of autogenous bone is challenging. Autologous platelet-rich plasma (PRP) has been widely considered for treatment, due to its potentially beneficial effect on bone regeneration and vascularization. The aim of the present study was to explore the effects of autogenous bone particles combined with PRP on repairing segmental bone defects in rabbits. Briefly, a critical-size diaphyseal radius defect was established in 45 New Zealand White rabbits. Animals were randomly divided into four groups, according to the different implants: Group A, empty bone defect; group B, PRP; group C, autogenous bone particles + bone mesenchymal stem cells (BMSCs) on the left radius; group D, autogenous bone particles + PRP + BMSCs on the right radius. Bone samples were collected and further analyzed using X-ray, histology and histomorphometry 4, 8 and 12 weeks post-surgery. In addition, the effect of PRP on cell proliferation was detected by Cell Counting Kit-8 and the concentrations of growth factors (GFs), transforming GF (TGF)-β1 and platelet-derived GF (PDGF), in PRP were verified by ELISA. X-ray, histology and histomorphometry data revealed that the fraction area of the newly formed bone was larger in group D. In addition, PRP could improve cell proliferation, osteogenic differentiation and the release of GFs, TGF-β1 and PDGF-AB. In conclusion, these findings indicated that an autogenous bone particle + PRP + BMSC scaffold may be used as a potential treatment strategy for segmental defects in humans.

Novel transplant of combined platelet-rich fibrin Releasate and bone marrow stem cells prevent bone loss in Ovariectomized osteoporotic mice

BACKGROUND

Osteoporosis is a metabolic bone disorder characterized by deterioration in the quantity and quality of bone tissue, with a consequent increase susceptibility to fracture.

METHODS

In this study, we sought to determine the efficacy of platelet-rich fibrin releasates (PRFr) in augmenting the therapeutic effects of stem cell-based therapy in treating osteoporotic bone disorder. An osteoporosis mouse model was established through bilateral ovariectomy on 12-week-old female ICR (Institute of Cancer Research) mice. Eight weeks postoperatively, the ovariectomized (OVX) mice were left untreated (control) or injected with PRFr, bone marrow stem cells (BMSCs), or the combination of BMSCs and PRFr. Two different injection (single versus quadruple) dosages were tested to investigate the accumulative effects of BMSCS and PRFr on bone quality. Eight weeks after injection, the changes in tibial microstructural profiles included the percentage of bone volume versus total tissue volume (BV/TV, %), bone mineral density (BMD, g/cm3), trabecular number (Tb.N, number/mm), and trabecular separation (Tb.Sp, mm) and bony histology were analyzed.

RESULTS

Postmenopausal osteoporosis model was successfully established in OVX mice, evidenced by reduced BMD, decreased BV/TV, lower Tb.N but increased Tb.Sp. Eight weeks after injection, there was no significant change to BMD and bone trabeculae could be detected in mice that received single-injection regimen. In contrast, in mice which received 4 doses of combined PRFr and BMSCs, the BMD, BV/TV, and TB.N increased, and the TB.Sp decreased significantly compared to untreated OVX mice. Moreover, the histological analysis showed the trabecular spacing become narrower in OVX-mice treated with quadruple injection of BMSCs and combined PRFr and BMSCs than untreated control.

CONCLUSION

The systemic administration of combined BMSCs and PRFr protected against OVX-induced bone mass loss in mice. Moreover, the improvement of bony profile scores in quadruple-injection group is better than the single-injection group, probably through the increase in effect size of cells and growth factors. Our data also revealed the combination therapy of BMSCs and PRFr has better effect in enhancing osteogenesis, which may provide insight for the development of a novel therapeutic strategy in osteoporosis treatment.

3D-HA Scaffold Functionalized by Extracellular Matrix of Stem Cells Promotes Bone Repair

BACKGROUND AND PURPOSE

The extracellular matrix (ECM) derived from bone marrow mesenchymal stem cells (BMSCs) has been used in regenerative medicine because of its good biological activity; however, its poor mechanical properties limit its application in bone regeneration. The purpose of this study is to construct a three dimensional-printed hydroxyapatite (3D-HA)/BMSC-ECM composite scaffold that not only has biological activity but also sufficient mechanical strength and reasonably distributed spatial structure.

METHODS

A BMSC-ECM was first extracted and formed into micron-sized particles, and then the ECM particles were modified onto the surface of 3D-HA scaffolds using an innovative linking method to generate composite 3D-HA/BMSC-ECM scaffolds. The 3D-HA scaffolds were used as the control group. The basic properties, biocompatibility and osteogenesis ability of both scaffolds were tested in vitro. Finally, a critical skull defect rat model was created and the osteogenesis effect of the scaffolds was evaluated in vivo.

RESULTS

The compressive modulus of the composite scaffolds reached 9.45±0.32 MPa, which was similar to that of the 3D-HA scaffolds (p>0.05). The pore size of the two scaffolds was 305±47 um and 315±34 um (p>0.05), respectively. A CCK-8 assay indicated that the scaffolds did not have cytotoxicity. The composite scaffolds had good cell adhesion ability, with a cell adhesion rate of up to 76.00±6.17% after culturing for 7 hours, while that of the 3D-HA scaffolds was 51.85±4.77% (p<0.01). In addition, the composite scaffold displayed higher alkaline phosphatase (ALP) activity, osteogenesis-related mRNA expression, and calcium nodule formation, thus confirming that the composite scaffolds had good osteogenic activity. The composite scaffolds exhibited good bone repair in vivo and were superior to the 3D-HA scaffolds.

CONCLUSION

We conclude that BMSC-ECM is a good osteogenic material and that the composite scaffolds have good osteogenic ability, which provides a new method and concept for the repair of bone defects.

Relationships of handgrip strength with the presence of cerebral microbleeds and platelet count in older Japanese adults

Introduction: Lower handgrip strength is a manifestation of sarcopenia and frailty, and has been reported to be associated with cerebral microbleeds (CMBs), which appear on T2^*-weighted magnetic resonance scans as low-intensity spots. However, the underlying mechanism is unknown. We hypothesized that vascular endothelial injury could be the common factor in loss of handgrip strength and CMBs. We aimed to clarify the relationship between handgrip strength and CMBs, with reference to a marker of vascular repair capability.

Materials and Methods: We conducted a cross-sectional study of 95 60- to 87-year-old Japanese people who underwent brain magnetic resonance imaging in 2016–2017. Baseline information was obtained by trained interviewers regarding the age, sex, smoking status, nutrient intake, cognition, medical history, education, and household income of the participants. Physical activity was assessed using a tri-axial accelerometer. We used the Fried frailty phenotype definition. Multivariable linear regression analysis was performed.

Results: Handgrip strength was independently associated with the presence of CMB after adjustment for age, sex, body mass index, classical cardiovascular risk factors, protein intake, and daily activity (B = −3.43, p = 0.027). This association was shown in participants with a low (B = −4.05, p = 0.045) but not high platelet count (B=−2.23, p = 0.479). Frailty was also independently associated with the presence of CMB after adjustment for confounders (B = 0.57, p = 0.014). Although this association was not present in participants a high platelet count, there was a positive trend in those with a low platelet count (B = 0.50, p = 0.135).

Conclusions: Platelet count, a marker of vascular repair capability, appears to modify the relationship between handgrip strength and CMBs.

Augmentation of Tendon Graft-Bone Tunnel Interface Healing by Use of Bioactive Platelet-Rich Fibrin Scaffolds

BACKGROUND

Platelet-rich fibrin (PRF) is a bioactive biomaterial wherein cytokines are enmeshed within the interconnecting fibrin network. PRF can be fabricated into a patch to augment healing of the interface between a tendon graft and bone tunnel.

HYPOTHESIS

The bioactivity of a PRF scaffold is preserved after PRF is mechanically compressed into a patch. A bioactive PRF patch could promote the incorporation of a tendon graft within the bone tunnel through the formation of a tendon-bone healing zone composed of both fibrocartilaginous tissue and new bone.

STUDY DESIGN

Controlled laboratory study.

METHODS

Bioactivity of PRF was evaluated through treatment of rabbit tenocytes with PRF-conditioned medium and cultivation of cells on a PRF patch. Cellular morphologic features, viability, and differentiation were analyzed accordingly. In an animal study, a rabbit tendon-bone healing model was established through use of New Zealand White rabbits. The implanted tendon graft was enveloped circumferentially with a bioactive PRF patch before being pulled through a bone tunnel in the proximal tibia. Micro-computed tomography (micro-CT) imaging and histological and biomechanical analyses of the tendon-bone interface were performed at 12 weeks postoperatively.

RESULTS

PRF improved the viability of the cultured tenocytes. The effects of PRF on in vitro mineralization of tenocytes were comparable with the effects of standard culture medium. The gene expressions of type I collagen and osteopontin were upregulated upon PRF treatment. For the in vivo study, micro-CT images revealed significant new bone synthesis at the tendon-bone interface in the PRF-enveloped group. The tendon-bone healing zone was characterized by abundant fibrocartilage tissue and new bone formation as demonstrated by histological analysis. Biomechanical testing showed significantly higher ultimate loads in the PRF-enveloped group.

CONCLUSION

Bioactive PRF could effectively augment healing of tendon graft to bone by inducing the formation of a transitional tendon-bone healing zone composed of fibrocartilage and bone.

CLINICAL RELEVANCE

Complete healing of the tendon graft in the bone tunnel is a prerequisite for successful ligament reconstruction, which would allow early and aggressive rehabilitation and rapid return to preinjury activity level. From a translational standpoint, the PRF-augmented healing in this rabbit animal model showed a promising biological approach to enhance tendon graft to bone healing via promotion of the functional anchorage between the 2 different materials.

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.

Platelets as an indicator of vascular repair in elderly Japanese men

Platelets and circulating CD34-positive cells have been reported to contribute to vascular repair (endothelial repair and developing atherosclerosis). And because hypertension is known to be a strong vascular impairment factors, it should also influence the respective numbers of these factors. To clarify the clinical importance of platelets on vascular repair, we conducted a cross-sectional study of 567 Japanese men aged 60-69 who underwent an annual health check-up between 2013 and 2015. Multiple linear regression analysis of non-hypertensive subjects adjusting for classical cardiovascular risk factors showed that although platelet count did not significantly correlate with carotid intima media thickness (β = −0.05, p = 0.356), it did positively correlate significantly with the natural log of the number of circulating CD34-positive cells (β = 0.26, p < 0.001). In hypertensive subjects, a significant positive correlation was seen between platelets and intima media thickness (β = 0.19, p = 0.008), whereas no significant correlation was seen between platelet count and the natural log of the number of circulating CD34-positive cells (β = 0.11, p = 0.119). Our results indicate that platelet count is an indicator of vascular repair activity (endothelial repair and developing atherosclerosis). Additionally, hypertension might mask the beneficial effects of circulating CD34-positive cells.

Possible mechanism underlying the association between height and vascular remodeling in elderly Japanese men

Height is reported to be inversely associated with cardiovascular disease. And platelets play an important role in vascular remodeling by supporting CD34-positive cells. To clarify the association between height and platelet, we conducted a cross-sectional study of 219 elderly Japanese men. Since hemoglobin concentration is influenced by vascular remodeling activity, an analysis stratified by hemoglobin level was performed. An inverse association was seen between height and platelet count in 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 = -0.22, p = 0.019 for subjects with high hemoglobin, and β = -0.01, p = 0.931 for subjects with low hemoglobin. We also found a positive association between platelets and carotid intima media thickness (CIMT) and circulating CD34-positive cells in subjects with high hemoglobin (partial correlation coefficient (r) = 0.21, p = 0.037 and r = 0.40, p =< 0.001), but not in subjects with low hemoglobin (r = 0.04, p = 0.710 and r = 0.06, p = 0.544). In subjects with a high hemoglobin concentration, platelets were inversely associated with height, and positively associated with CIMT and circulating CD34-positive cells. These results indicate that subjects with a short stature activate vascular remodeling to a much greater extent than subjects with a tall stature.

Bone marrow stem cells-derived extracellular matrix is a promising material

The extracellular matrix(ECM), which is primarily composed of collagens and proteoglycans, plays a key role in cell proliferation, differentiation, and migration and interactions between cells. In this study, we produced chitosan/gelatin/bone marrow stem cells-derived extracellular matrix(C/G/BMSCs-dECM) scaffolds via lyophilization and cross-linking, and chitosan/gelatin(C/G) scaffolds were used as controls. For the C/G/BMSCs-dECM scaffolds, the average pore size was 289.17 ± 80.28 μm; the average porosity was 89.25 ± 3.75%; the average compressive modulus was 0.82 ± 0.07 MPa; and the average water uptake ratio was 13.81 ± 1.00. In vitro, the C/G/BMSCs-dECM scaffolds promoted bone marrow stem cells(BMSCs) attachment and proliferation. Moreover, improved osteogenic differentiation was observed for these scaffolds. Thus, C/G/BMSCs-dECM is a promising material for bone tissue engineering.

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.

Application of platelet-rich plasma with stem cells in bone and periodontal tissue engineering

Presently, there is a high paucity of bone grafts in the United States and worldwide. Regenerating bone is of prime concern due to the current demand of bone grafts and the increasing number of diseases causing bone loss. Autogenous bone is the present gold standard of bone regeneration. However, disadvantages like donor site morbidity and its decreased availability limit its use. Even allografts and synthetic grafting materials have their own limitations. As certain specific stem cells can be directed to differentiate into an osteoblastic lineage in the presence of growth factors (GFs), it makes stem cells the ideal agents for bone regeneration. Furthermore, platelet-rich plasma (PRP), which can be easily isolated from whole blood, is often used for bone regeneration, wound healing and bone defect repair. When stem cells are combined with PRP in the presence of GFs, they are able to promote osteogenesis. This review provides in-depth knowledge regarding the use of stem cells and PRP in vitro, in vivo and their application in clinical studies in the future.

Combination of platelet-rich plasma and bone marrow mesenchymal stem cells enhances tendon-bone healing in a rabbit model of anterior cruciate ligament reconstruction

Background

The objective of this study was to investigate the potency of platelet-rich plasma (PRP) combined with bone marrow mesenchymal stem cells (BMSCs) to promote tendon–bone healing in a rabbit model.

Methods

In the in vitro study, the effects of PRP on osteogenic induction of BMSCs were analysed. Later, PRP with or without BMSCs was used in the rabbit model of anterior cruciate ligament reconstruction. Specimens were harvested 8 weeks postoperatively to evaluate tendon–bone healing by histology, radiology, and biomechanical testing.

Results

The in vitro study revealed that collagen I, osteocalcin, and osteopontin expression was higher in BMSCs co-cultured with PRP for 14 days. The in vivo study revealed a more mature tendon–bone interface using light microscopy, a more newly formed bone at the bone tunnel walls detected by micro-computed tomography, and a significantly higher failure load as assessed by biomechanical testing in the BMSC + PRP group than in the control and PRP groups.

Conclusions

These results indicate that the combination of PRP and BMSCs promotes tendon–bone healing and has potential for clinical use.

Electronic supplementary material

The online version of this article (doi:10.1186/s13018-016-0433-7) contains supplementary material, which is available to authorized users.

The Chondrogenic Induction Potential for Bone Marrow-Derived Stem Cells between Autologous Platelet-Rich Plasma and Common Chondrogenic Induction Agents: A Preliminary Comparative Study

The interests in platelet-rich plasma (PRP) and their application in stem cell therapy have contributed to a better understanding of the basic biology of the prochondrogenesis effect on bone marrow-derived stem cells (BMSCs). We aimed at comparing the effect of autologous PRP with common chondrogenic induction agents (CCIAs) on the chondrogenic differentiation of BMSCs. Rabbit BMSCs were isolated and characterized by flow cytometry and differentiated towards adipocytes and osteoblasts. The chondrogenic response of BMSCs to autologous PRP and CCIAs which included transforming growth factor-β1 (TGF-β1), dexamethasone (DEX), and vitamin C (Vc) was examined by cell pellet culture. The isolated BMSCs after two passages highly expressed CD29 and CD44 but minimally expressed CD45. The osteogenic and adipogenic differentiation potentials of the isolated BMSCs were also confirmed. Compared with common CCIAs, autologous PRP significantly upregulated the chondrogenic related gene expression, including Col-2, AGC, and Sox-9. Osteogenic related gene expression, including Col-1 and OCN, was not of statistical significance between these two groups. Thus, our data shows that, compared with common chondrogenic induction agents, autologous PRP can be more effective in promoting the chondrogenesis of BMSCs.