Prevalence and development of aortic dilation and dissection in women with Turner syndrome: a systematic review and meta-analysis.

OBJECTIVES: Women with Turner syndrome (TS) have an increased risk of aortic disease, reducing life-expectancy. This study aimed to systematically review the prevalence of thoracic aortic dilatation, aortic dimensions and growth, and the incidence of aortic dissection. METHODS: A systematic literature search was conducted up to July 2022. Observational studies with an adult TS population were included, and studies including children aged <15 years old or specific TS populations were excluded. RESULTS: In total 21 studies were included. The pooled prevalence of ascending aortic dilatation was 23% (95% CI 19-26) at a mean pooled age of 29 years (95% CI 26-32), while the incidence of aortic dissection was 164 per 100.000 patient-years (95% CI 95-284). Three reporting studies showed aortic growth over time to be limited. Risk factors for aortic dilation or dissection were older age, bicuspid aortic valve, aortic coarctation, and hypertension. CONCLUSION: In adult TS women, ascending aortic dilatation is common and the hazard of aortic dissection increased compared to the general population, whereas aortic growth is limited. Conventional risk markers do not explain all aortic dissection cases; therefore, new imaging parameters and blood biomarkers are needed to improve prediction, allowing for patient-tailored follow-up and surgical decision-making.

Recall bias in pain scores evaluating abdominal wall and groin pain surgery.

PURPOSE: To determine whether levels of pre-operative pain as recalled by a patient in the post-operative phase are possibly overestimated or underestimated compared to prospectively scored pain levels. If so, a subsequent misclassification may induce recall bias that may lead to an erroneous effect outcome. METHODS: Data of seven retrospective cohort studies on surgery for chronic abdominal wall and groin pain using three different pain scores were systematically analyzed. First, it was assessed whether retrospectively acquired pre-operative pain levels, as scored by the patient in the post-operative phase, differed from prospectively obtained pre-operative pain scores. Second, it was determined if errors associated with retrospectively obtained pain scores potentially lead to a misclassification of treatment outcome. Third, a meta-analysis established whether recall misclassifications, if present, affected overall study conclusions. RESULTS: Pain data of 313 patients undergoing remedial surgery were evaluated. The overall prevalence of misclassification due to a recall error was 13.7%. Patients not benefitting from surgery ('failures') judged their pre-operative pain level as more severe than it actually was. In contrast, patients who were pain free after remedial surgery ('successes') underestimated pre-operative pain scores. Recall misclassifications were significantly more present in failures than in successful patients (odds ratio 2.4 [95% CI 1.2-4.8]). CONCLUSION: One in seven patients undergoing remedial groin surgery is misclassified on the basis of retrospectively obtained pre-operative pain scores (success instead of failure, or vice versa). Misclassifications are relatively more present in failures after surgery. Therefore, the effect size of a therapy erroneously depends on its success rate.

From benchtop to clinic: a translational analysis of the immune response to submicron topography and its relevance to bone healing.

Proper regulation of the innate immune response to bone biomaterials after implantation is pivotal for successful bone healing. Pro-inflammatory M1 and anti-inflammatory M2 macrophages are known to have an important role in regulating the healing response to biomaterials. Materials with defined structural and topographical features have recently been found to favourably modulate the innate immune response, leading to improved healing outcomes. Calcium phosphate bone grafts with submicron-sized needle-shaped surface features have been shown to trigger a pro-healing response through upregulation of M2 polarised macrophages, leading to accelerated and enhanced bone regeneration. The present review describes the recent research on these and other materials, all the way from benchtop to the clinic, including in vitro and in vivo fundamental studies, evaluation in clinically relevant spinal fusion models and clinical validation in a case series of 77 patients with posterolateral and/or interbody fusion in the lumbar and cervical spine. This research demonstrates the feasibility of enhancing biomaterial-directed bone formation by modulating the innate immune response through topographic surface features.

Accelerated bone formation by biphasic calcium phosphate with a novel sub-micron surface topography.

Osteoinductive calcium phosphate (CaP) bone grafts have equivalent performance to autografts in repairing critical-size bone defects. The osteoinductive potential of CaP is linked to the size of the surface topographical features. In the present study, two novel biphasic calcium phosphate (BCP) bone grafts were synthesised with either sub-micron- (BCP<µm) or micron-scale (BCPµm) needle-shaped surface topography and compared to dimensionally similar tricalcium phosphate (TCP) with grain-shaped surface structures (TCP<µm and TCPµm). To clarify the possible function of the surface morphology (needle-like vs. grain-like) in initiating bone formation, the four CaP test materials were physicochemically characterised and implanted for 12 weeks in the dorsal muscle of beagles. The sub-micron needle-shaped topography of BCP<µm triggered earlier bone formation (3-6 weeks) as compared to the grain-shaped surface topography of TCP<µm, which formed bone at 6-9 weeks. After 12 weeks, the amount of induced bone formation in both materials was equivalent, based on histomorphometry. The micron-sized needle-shaped surface topography of BCPµm led to limited formation of new bone tissue, whereas its counterpart, TCPµm with grain-shaped surface topography, failed to trigger de novo bone formation. The relative strength of the parameters affecting CaP-driven bone induction was as follows: surface feature size > surface feature morphology > substrate chemistry. BCP materials with needle-shaped sub-micron surface topography gave rise to accelerated bone formation and slower rate of resorption than a comparable TCP. These characteristics may be translated to improve bone healing in orthotopic defects.

Evaluation of fine organic mixtures for treatment of acid mine drainage in sulfidogenic reactors.

The performance of passive biochemical reactors in acid mine drainage (AMD) treatment could be enhanced by using fine organic substrates in new reactor designs, such as diffusive exchange reactors. This work evaluated the effect of fine cellulosic components in organic mixtures and of enrichment with inoculum, on sulfate and metals removal in discontinuous cultures for three types of synthetic AMD. The cellulosic substrates evaluated were sawdust, microcrystalline cellulose, and forestry cellulose fibers, supplemented with cow manure and leaf compost. Using microcrystalline cellulose and forestry cellulose fibers with the less concentrated AMD, high sulfate reduction rates (73 mg/L-d and 58.2 mg/L-d, respectively) were achieved. Correspondingly, iron concentrations were reduced by 69% and 86.6%. Based on their higher sulfate reducing capacity, cellulose fibers obtained as fiber boards from a local kraft pulp mill were selected for treating a synthetic AMD with a high copper concentration (273 mg/L) and pH 4.94. In batch culture, low sulfate reducing activity (13.10 mg/L-d) was only observed at the highest substrate/AMD ratio (0.5:10) tested. Results show that the use of forestry cellulose fibers in reactive mixtures supplemented with inoculum could be an alternative for optimization of diffusive exchange reactors for AMD treatment.

Are the Chinese Saving for Old Age?: The Relationship between Future Pension Benefits of 45-60 Years Old Chinese and Current Household Expenditures.

Worldwide, older people's support used to be the adult children's responsibility. In China, two generations after introducing the one-child policy in the late 70-ies, this becomes an increasingly demanding obligation. The Chinese government took the responsibility to mitigating old- age poverty risks and realized unprecedented progress in pension coverage. At the same time, the household savings increased to about 30 % of disposable income. Built on previous research on the politics of ageing, this study analyses households responses to the established governmental and firm pension programs as well as to the New Rural Pension Scheme (NRPS), introduced in 2009. The central question is: will participation in the established and new pension programs lead to higher current Chinese household expenditures and therefore to lower savings? The China Health and Retirement Longitudinal Study (CHARLS) dataset of 2011 offered the opportunity to study the influence of the recently introduced NRPS. We find that Chinese households with members between 45 and 60 years who expect future benefits of NRPS do not have higher expenditures than those not covered by NRPS. For the participants in the established, mostly urban pension programs a correlation was found with higher current expenditures (28 % more spending on basic needs, 80 % more on luxury) However, further analysis shows that this correlation cannot be interpreted as a causal relationship. This implies that coverage by pensions, be it in urban or rural programs, does not determine higher current expenditures and lower savings.

Surface-enrichment with hydroxyapatite nanoparticles in stereolithography-fabricated composite polymer scaffolds promotes bone repair.

Fabrication of composite scaffolds using stereolithography (SLA) for bone tissue engineering has shown great promises. However, in order to trigger effective bone formation and implant integration, exogenous growth factors are commonly combined to scaffold materials. In this study, we fabricated biodegradable composite scaffolds using SLA and endowed them with osteopromotive properties in the absence of biologics. First we prepared photo-crosslinkable poly(trimethylene carbonate) (PTMC) resins containing 20 and 40wt% of hydroxyapatite (HA) nanoparticles and fabricated scaffolds with controlled macro-architecture. Then, we conducted experiments to investigate how the incorporation of HA in photo-crosslinked PTMC matrices improved human bone marrow stem cells osteogenic differentiation in vitro and kinetic of bone healing in vivo. We observed that bone regeneration was significantly improved using composite scaffolds containing as low as 20wt% of HA, along with difference in terms of osteogenesis and degree of implant osseointegration. Further investigations revealed that SLA process was responsible for the formation of a rich microscale layer of HA corralling scaffolds. To summarize, this work is of substantial importance as it shows how the fabrication of hierarchical biomaterials via surface-enrichment of functional HA nanoparticles in composite polymer stereolithographic structures could impact in vitro and in vivo osteogenesis. STATEMENT OF SIGNIFICANCE: This study reports for the first time the enhance osteopromotion of composite biomaterials, with controlled macro-architecture and microscale distribution of hydroxyapatite particles, manufactured by stereolithography. In this process, the hydroxyapatite particles are not only embedded into an erodible polymer matrix, as reported so far in the literature, but concentrated at the surface of the structures. This leads to robust in vivo bone formation at low concentration of hydroxyapatite. The reported 3D self-corralling composite architecture provides significant opportunities to develop functional biomaterials for bone repair and tissue engineering.

Modeling BCR-ABL and MLL-AF9 leukemia in a human bone marrow-like scaffold-based xenograft model.

Although NOD-SCID IL2Rγ-/- (NSG) xenograft mice are currently the most frequently used model to study human leukemia in vivo, the absence of a human niche severely hampers faithful recapitulation of the disease. We used NSG mice in which ceramic scaffolds seeded with human mesenchymal stromal cells were implanted to generate a human bone marrow (huBM-sc)-like niche. We observed that, in contrast to the murine bone marrow (mBM) niche, the expression of BCR-ABL or MLL-AF9 was sufficient to induce both primary acute myeloid leukemia (AML) and acute lymphocytic leukemia (ALL). Stemness was preserved within the human niches as demonstrated by serial transplantation assays. Efficient engraftment of AML MLL-AF9 and blast-crisis chronic myeloid leukemia patient cells was also observed, whereby the immature blast-like phenotype was maintained in the huBM-sc niche but to a much lesser extent in mBM niches. We compared transcriptomes of leukemias derived from mBM niches versus leukemias from huBM-like scaffold-based niches, which revealed striking differences in the expression of genes associated with hypoxia, mitochondria and metabolism. Finally, we utilized the huBM-sc MLL-AF9 B-ALL model to evaluate the efficacy of the I-BET151 inhibitor in vivo. In conclusion, we have established human niche models in which the myeloid and lymphoid features of BCR-ABL+ and MLL-AF9+ leukemias can be studied in detail.

Influence of surface microstructure and chemistry on osteoinduction and osteoclastogenesis by biphasic calcium phosphate discs.

It has been reported that surface microstructural dimensions can influence the osteoinductivity of calcium phosphates (CaPs), and osteoclasts may play a role in this process. We hypothesised that surface structural dimensions of ≤ 1 µm trigger osteoinduction and osteoclast formation irrespective of macrostructure (e.g., concavities, interconnected macropores, interparticle space) or surface chemistry. To test this, planar discs made of biphasic calcium phosphate (BCP: 80% hydroxyapatite, 20% tricalcium phosphate) were prepared with different surface structural dimensions - either ~ 1 µm (BCP1150) or ~ 2-4 µm (BCP1300) - and no macropores or concavities. A third material was made by sputter coating BCP1150 with titanium (BCP1150Ti), thereby changing its surface chemistry but preserving its surface structure and chemical reactivity. After intramuscular implantation in 5 dogs for 12 weeks, BCP1150 formed ectopic bone in 4 out of 5 samples, BCP1150Ti formed ectopic bone in 3 out of 5 samples, and BCP1300 formed no ectopic bone in any of the 5 samples. In vivo, large multinucleated osteoclast-like cells densely colonised BCP1150, smaller osteoclast-like cells formed on BCP1150Ti, and osteoclast-like cells scarcely formed on BCP1300. In vitro, RAW264.7 cells cultured on the surface of BCP1150 and BCP1150Ti in the presence of osteoclast differentiation factor RANKL (receptor activator for NF-κB ligand) proliferated then differentiated into multinucleated osteoclast-like cells with positive tartrate resistant acid phosphatase (TRAP) activity. However, cell proliferation, fusion, and TRAP activity were all significantly inhibited on BCP1300. These results indicate that of the material parameters tested - namely, surface microstructure, macrostructure, and surface chemistry - microstructural dimensions are critical in promoting osteoclastogenesis and triggering ectopic bone formation.

Influence of fluoride in poly(d,l-lactide)/apatite composites on bone formation.

The influence of fluoride in poly(d,l-lactide)/apatite composites on ectopic bone formation was evaluated in sheep. Nano-apatite powders with different replacement levels of OH groups by fluoride (F) (0% (F0), 50% (F50), 100% (F100), and excessive (F200)) were co-extruded with poly (d,l-lactide) at a weight ratio of 1:1. Fluoride release from the composites (CF0, CF50, CF100, and CF200) was evaluated in vitro and bone formation was assessed after intramuscular implantation in sheep. After 24 weeks in simulated physiological solution, CF0 and CF50 showed negligible fluoride release, whereas it was considerable from the CF100 and CF200 composites. Histology showed that the incidence of de novo bone formation decreased in implants with increasing fluoride content indicating a negative influence of fluoride on ectopic bone formation. Furthermore, a significant decrease in resorption of the high fluoride-content composites and a reduction in the number of multinucleated giant cells were seen. These results show that instead of promoting, the presence of fluoride in poly(d,l-lactide)/apatite composites seemed to suppresses their resorption and osteoinductive potential in non-osseous sites.

Submicron-scale surface architecture of tricalcium phosphate directs osteogenesis in vitro and in vivo.

A current challenge of synthetic bone graft substitute design is to induce bone formation at a similar rate to its biological resorption, matching bone's intrinsic osteoinductivity and capacity for remodelling. We hypothesise that both osteoinduction and resorption can be achieved by altering surface microstructure of beta-tricalcium phosphate (TCP). To test this, two TCP ceramics are engineered with equivalent chemistry and macrostructure but with either submicron- or micron-scale surface architecture. In vitro, submicron-scale surface architecture differentiates larger, more active osteoclasts--a cell type shown to be important for both TCP resorption and osteogenesis--and enhances their secretion of osteogenic factors to induce osteoblast differentiation of human mesenchymal stem cells. In an intramuscular model, submicrostructured TCP forms 20 % bone in the free space, is resorbed by 24 %, and is densely populated by multinucleated osteoclast-like cells after 12 weeks; however, TCP with micron-scale surface architecture forms no bone, is essentially not resorbed, and contains scarce osteoclast-like cells. Thus, a novel submicron-structured TCP induces substantial bone formation and is resorbed at an equivalent rate, potentially through the control of osteoclast-like cells.

Poly(trimethylene carbonate) and biphasic calcium phosphate composites for orbital floor reconstruction: a feasibility study in sheep.

In the treatment of orbital floor fractures, bone is ideally regenerated. The materials currently used for orbital floor reconstruction do not lead to the regeneration of bone. Our objective was to render polymeric materials based on poly(trimethylene carbonate) (PTMC) osteoinductive, and to evaluate their suitability for use in orbital floor reconstruction. For this purpose, osteoinductive biphasic calcium phosphate (BCP) particles were introduced into a polymeric PTMC matrix. Composite sheets containing 50 wt% BCP particles were prepared. Also laminates with poly(D,L-lactide) (PDLLA) were prepared by compression moulding PDLLA films onto the composite sheets. After sterilisation by gamma irradiation, the sheets were used to reconstruct surgically-created orbital floor defects in sheep. The bone inducing potential of the different implants was assessed upon intramuscular implantation. The performance of the implants in orbital floor reconstruction was assessed by cone beam computed tomography (CBCT). Histological evaluation revealed that in the orbital and intramuscular implantations of BCP containing specimens, bone formation could be seen after 3 and 9 months. Analysis of the CBCT scans showed that the composite PTMC sheets and the laminated composite sheets performed well in orbital floor reconstruction. It is concluded that PTMC/BCP composites and PTMC/BCP composites laminated with PDLLA have osteoinductive properties and seem suitable for use in orbital floor reconstruction.

Child abuse: a common problem in Curaçao? / Abuso infantil: ¿Un problema común en Curazao?

OBJECTIVE: To assess the prevalence of child abuse among high school students in Curaçao. METHODS: A questionnaire survey among high school students up to 17 years of age was conducted. The questionnaire was based on existing literature and validated questionnaires. The questionnaire used was analysed and adapted to the situation in Curaçao by a panel of experts on child abuse. The primary objective was to gain insight into the incidence, prevalence and various forms of child abuse among students in Curaçao. Five forms of child abuse are distinguished in the literature: physical abuse, emotional abuse, sexual abuse, neglect and exploitation. Furthermore, the degree of confidence of the students in general practitioners (GPs) as care providers in the field of child abuse was explored. RESULTS: Questionnaires from 545 of the 628 respondents were included. In total, 43% of the respondents had ever-experienced an event which could be defined as (a form of) child abuse. More than one-third of the respondents reporting child abuse ever had an experience that could be interpreted as physical abuse. More than 15% of the respondents reporting child abuse had experienced sexual abuse. Girls experienced significantly more sexual abuse than boys. Emotional abuse in the last year was experienced by 3% of the respondents. One per cent of the respondents ever-experienced neglect. according to most respondents, GPs were not seen as care providers in cases of child abuse; they believed that GPs were mainly to be consulted for illnesses or physical symptoms and not for forms of child abuse. CONCLUSION: The prevalence of ever-having-experienced a form of child abuse is estimated at 431 per 1000 students. Child abuse, particularly physical abuse, is common in Curaçao, and is probably comparable to other surrounding countries. General practitioners were not seen as care providers in identifying and reporting cases of child abuse according to most respondents.

OBJETIVO: Evaluar la prevalencia del abuso infantil entre estudiantes de secundaria en Curazao. MÉTODOS: Se aplicó un cuestionario entre estudiantes de secundaria de hasta 17 años de edad. El cuestionario se basó en la literatura existente y cuestionarios validados. El cuestionario usado fue analizado y adaptado a la situación de Curazao por un panel de expertos en abuso infantil. El objetivo principal fue profundizar los conocimientos acerca de la incidencia, prevalencia y diversas formas de abuso infantil entre estudiantes en Curazao. La literatura distingue cinco formas de abuso infantil: abuso físico, abuso emocional, abuso sexual, negligencia y explotación. Además, se exploró el grado de confianza de los estudiantes en los médicos generales (MGs) como proveedores de cuidado en el área del abuso infantil. RESULTADOS: Se incluyeron los cuestionarios de 545 de los 628 encuestados. En total, 43% de los encuestados nunca habían pasado por una experiencia que pudiera interpretarse como (forma de) abuso infantil. Más de un tercio de los encuestados a los que se les pidió reportar abuso infantil, jamás había tenido una experiencia que pudira interpretarse como abuso físico. Más del 15% de los encuestados sobre abuso infantil habían experimentado abuso sexual. Las niñas experimentaron significativamente más abuso sexual que los niños. El abuso emocional en el último año fue experimentado por 3% de los encuestados. El uno por ciento de los encuestados jamás experimentó negligencia. Los médicos generales no eran vistos como proveedores de cuidado en los casos de abuso infantil, de acuerdo con la mayoría de los encuestados. Según ellos, los MGs deben ser consultados principalmente en el caso de enfermedades o síntomas físicos, y no en casos de formas de abuso infantil. CONCLUSIÓN: La prevalencia de nunca haber experimentado una forma de maltrato infantil se estima en 431 por 1000 estudiantes. El abuso infantil, en particular el abuso físico, es común en Curazao, y es probablemente comparable a otros países circundantes. Los médicos generales no eran vistos como proveedores de cuidado en cuanto a identificar y reportar casos de abuso infantil, según la mayor parte de los encuestados.

Child abuse: a common problem in Curaçao?

OBJECTIVE: To assess the prevalence of child abuse among high school students in Curacao. METHODS: A questionnaire survey among high school students up to 17 years of age was conducted. The questionnaire was based on existing literature and validated questionnaires. The questionnaire used was analysed and adapted to the situation in Curaçao by a panel of experts on child abuse. The primary objective was to gain insight into the incidence, prevalence and various forms of child abuse among students in Curaçao. Five forms of child abuse are distinguished in the literature: physical abuse, emotional abuse, sexual abuse, neglect and exploitation. Furthermore, the degree of confidence of the students in general practitioners (GPs) as care providers in the field of child abuse was explored. RESULTS: Questionnaires from 545 of the 628 respondents were included. In total, 43% of the respondents had ever-experienced an event which could be defined as (a form of) child abuse. More than one-third of the respondents reporting child abuse ever had an experience that could be interpreted as physical abuse. More than 15% of the respondents reporting child abuse had experienced sexual abuse. Girls experienced significantly more sexual abuse than boys. Emotional abuse in the last year was experienced by 3% of the respondents. One per cent of the respondents ever-experienced neglect. According to most respondents, GPs were not seen as care providers in cases of child abuse; they believed that GPs were mainly to be consulted for illnesses or physical symptoms and not for forms of child abuse. CONCLUSION: The prevalence of ever-having-experienced a form of child abuse is estimated at 431 per 1000 students. Child abuse, particularly physical abuse, is common in Curaçao, and is probably comparable to other surrounding countries. General practitioners were not seen as care providers in identifying and reporting cases of child abuse according to most respondents.

Risk factors for domestic violence in Curacao.

One out of three people (25% of men, 38% of women) in Curacao have experienced some form of domestic violence at some point in their adult lives. The most significant risk factors for domestic violence in Curacao are the female gender, a young age, low education, and experiencing domestic violence victimization in childhood. Divorce, single parenthood, and unemployment increase the risk for women, but not for men. These findings are consistent with current literature on the subject. Further research on the context, nature, and severity of domestic violence in the Caribbean is necessary. Studies should preferably combine the strengths of national crime surveys and family conflict studies: nationally representative samples (including men and women) and questionnaires that include all possible experiences of psychological, physical, and sexual assaults by current and former partners, family, and friends.

Contraception and induced abortion in the West Indies: a review.

BACKGROUND: Most islands in the West Indies do not have liberal laws on abortion, nor laws on pregnancy prevention programmes (contraception). We present results of a literature review about the attitude of healthcare providers and women toward (emergency) contraception and induced abortion, prevalence, methods and juridical aspects of induced abortion and prevention policies. METHODS: Articles were obtained from PubMed, EMBASE, MEDLINE, PsychlNFO and Soclndex (1999 to 2010) using as keywords contraception, induced abortion, termination of pregnancy, medical abortion and West Indies. RESULTS: Thirty-seven articles met the inclusion criteria: 18 on contraception, 17 on induced abortion and two on both subjects. Main results indicated that healthcare providers' knowledge of emergency contraception was low. Studies showed a poor knowledge of contraception, but counselling increased its effective use. Exact numbers about prevalence of abortion were not found. The total annual number of abortions in the West Indies is estimated at 300 000; one in four pregnancies ends in an abortion. The use of misoprostol diminished the complications of unsafe abortions. Legislation of abortion varies widely in the different islands in the West Indies: Cuba, Puerto Rico, Martinique, Guadeloupe and St Martin have legal abortions. Barbados was the first English-speaking island with liberal legislation on abortion. All other islands have restrictive laws. CONCLUSION: Despite high estimated numbers of abortion, research on prevalence of abortion is missing. Studies showed a poor knowledge of contraception and low use among adolescents. Most West Indian islands have restrictive laws on abortion.

Scaffolds with a standardized macro-architecture fabricated from several calcium phosphate ceramics using an indirect rapid prototyping technique.

Calcium phosphate ceramics, commonly applied as bone graft substitutes, are a natural choice of scaffolding material for bone tissue engineering. Evidence shows that the chemical composition, macroporosity and microporosity of these ceramics influences their behavior as bone graft substitutes and bone tissue engineering scaffolds but little has been done to optimize these parameters. One method of optimization is to place focus on a particular parameter by normalizing the influence, as much as possible, of confounding parameters. This is difficult to accomplish with traditional fabrication techniques. In this study we describe a design based rapid prototyping method of manufacturing scaffolds with virtually identical macroporous architectures from different calcium phosphate ceramic compositions. Beta-tricalcium phosphate, hydroxyapatite (at two sintering temperatures) and biphasic calcium phosphate scaffolds were manufactured. The macro- and micro-architectures of the scaffolds were characterized as well as the influence of the manufacturing method on the chemistries of the calcium phosphate compositions. The structural characteristics of the resulting scaffolds were remarkably similar. The manufacturing process had little influence on the composition of the materials except for the consistent but small addition of, or increase in, a beta-tricalcium phosphate phase. Among other applications, scaffolds produced by the method described provide a means of examining the influence of different calcium phosphate compositions while confidently excluding the influence of the macroporous structure of the scaffolds.

Heterotopic bone formation by nano-apatite containing poly(D,L-lactide) composites.

To render polymeric materials osteoinductive, nano-sized calcium phosphate apatite particles (CaP) were introduced into a low molecular weight poly(D,L-lactide). Homogenous composites were made with 10%, 20% and 40% by weight of apatite content while pure polylactide was used as control. Thereafter porous samples (pore size 300-400 microm, 60% porosity) were fabricated and sterilized. In vitro studies showed that calcium ions were released from the composites depending on the apatite content, while surface mineral deposition was observed only on the 40% CaP composites in simulated body fluid (SBF) within 14 days. After 12 weeks of intramuscular implantation in dogs, only the 40% CaP composite implant retained its shape and showed ectopic bone formation within the pores. In conclusion, adding a content of 40% apatite into poly(D,L-lactide) could lead to an osteoinductive material. Future studies will focus on understanding this phenomenon of material-directed osteoinduction in order to develop a promising bone graft substitute.

Human tissue-engineered bone produced in clinically relevant amounts using a semi-automated perfusion bioreactor system: a preliminary study.

The aim of this study was to evaluate a semi-automated perfusion bioreactor system for the production of clinically relevant amounts of human tissue-engineered bone. Human bone marrow stromal cells (hBMSCs) of eight donors were dynamically seeded and proliferated in a perfusion bioreactor system in clinically relevant volumes (10 cm(3)) of macroporous biphasic calcium phosphate scaffolds (BCP particles, 2-6 mm). Cell load and distribution were shown using methylene blue staining. MTT staining was used to demonstrate viability of the present cells. After 20 days of cultivation, the particles were covered with a homogeneous layer of viable cells. Online oxygen measurements confirmed the proliferation of hBMSCs in the bioreactor. After 20 days of cultivation, the hybrid constructs became interconnected and a dense layer of extracellular matrix was present, as visualized by scanning electron microscopy (SEM). Furthermore, the hBMSCs showed differentiation towards the osteogenic lineage as was indicated by collagen type I production and alkaline phosphatase (ALP) expression. We observed no significant differences in osteogenic gene expression profiles between static and dynamic conditions like ALP, BMP2, Id1, Id2, Smad6, collagen type I, osteocalcin, osteonectin and S100A4. For the donors that showed bone formation, dynamically cultured hybrid constructs showed the same amount of bone as the statically cultured hybrid constructs. Based on these results, we conclude that a semi-automated perfusion bioreactor system is capable of producing clinically relevant and viable amounts of human tissue-engineered bone that exhibit bone-forming potential after implantation in nude mice.

Expansion of human mesenchymal stromal cells on microcarriers: growth and metabolism.

Adult stem cells, or mesenchymal stromal cells (MSCs), are of great potential for cell therapy and tissue-engineering applications. However, for therapeutic use, these cells need to be isolated from tissue or a biopsy and efficiently expanded, as they cannot be harvested in sufficient quantities from the body. In our opinion, efficient expansion of MSCs can be achieved in a microcarrier-based cultivation system. This study selected a suitable microcarrier for human bone marrow-derived stromal cells (HBMSCs), optimized cell-seeding strategies by varying serum concentrations, and optimized dynamic expansion of the HBMSCs in a microcarrier-based spinner flask cultivation system by applying various feeding regimes. Cytodex 1 microcarriers in combination with a low-serum concentration (0-5%) in the medium resulted in the highest seeding efficiency for the HBMSCs. Subsequently, significant expansion of the HBMSCs on these carriers has been observed. The highest number of HBMSCs population doublings (4.8 doublings) was obtained by a combination of 50% medium refreshment combined with addition of 30% medium containing microcarriers every 3 days. Exponential cell growth was observed for at least 9 days after seeding, provided that sufficient nutrients (such as glucose) were present, metabolite concentrations (such as ammonia) were kept below growth-inhibitory concentrations and adequate surface area was present for the cells. After dynamic expansion of the HBMSCs, the cells retained their differentiation potential and their cell surface markers, indicating that HBMSCs expansion on Cytodex 1 microcarriers did not alter the phenotypic properties of the cells.