Generation of induced pluripotent stem cells (UCLi024-A) from a patient with argininosuccinate lyase deficiency carrying a homozygous c.437G > A (p.Arg146Gln) mutation

Argininosuccinic aciduria (ASA) is a rare inherited metabolic disease caused by argininosuccinate lyase (ASL) deficiency. Patients with ASA present with hyperammonaemia due to an impaired urea cycle pathway in the liver, and systemic disease with epileptic encephalopathy, chronic liver disease, and arterial hypertension. A human induced pluripotent stem cell (iPSC) line from the fibroblasts of a patient with ASA with homozygous pathogenic c.437G > A mutation of hASL was generated. Characterization of the cell line demonstrated pluripotency, differentiation potential and normal karyotype. This cell line, called UCLi024-A, can be utilized for in vitro disease modelling of ASA, and design of novel therapeutics.

New Developments and Challenges in Liver Transplantation

Liver disease is increasing in incidence and is the third most common cause of premature death in the United Kingdom and fourth in the United States. Liver disease accounts for 2 million deaths globally each year. Three-quarters of patients with liver disease are diagnosed at a late stage, with liver transplantation as the only definitive treatment. Thomas E. Starzl performed the first human liver transplant 60 years ago. It has since become an established treatment for end-stage liver disease, both acute and chronic, including metabolic diseases and primary and, at present piloting, secondary liver cancer. Advances in surgical and anaesthetic techniques, refined indications and contra-indications to transplantation, improved donor selection, immunosuppression and prognostic scoring have allowed the outcomes of liver transplantation to improve year on year. However, there are many limitations to liver transplantation. This review describes the milestones that have occurred in the development of liver transplantation, the current limitations and the ongoing research aimed at overcoming these challenges.

Ultrasound Histotripsy on a Viable Perfused Whole Porcine Liver: Histological Aspects, Including 3D Reconstruction of the Histotripsy Site

Non-invasive therapeutic-focused ultrasound (US) can be used for the mechanical dissociation of tissue and is described as histotripsy. We have performed US histotripsy in viable perfused ex vivo porcine livers as a step in the development of a novel approach to hepatocyte cell transplantation. The histotripsy nidus was created with a 2 MHz single-element focused US transducer, producing 50 pulses of 10 ms duration, with peak positive and negative pressure values of P+ = 77.7 MPa and P− = –13.7 MPaat focus, respectively, and a duty cycle of 1%. Here, we present the histological analysis, including 3D reconstruction of histotripsy sites. Five whole porcine livers were retrieved fresh from the abattoir using human transplant retrieval and cold static preservation techniques and were then perfused using an organ preservation circuit. Whilst under perfusion, histotripsy was performed to randomly selected sites on the live. Fifteen lesional sites were formalin-fixed and paraffin-embedded. Sections were stained with Haematoxylin and Eosin and picro-Sirius red, and they were also stained for reticulin. Additionally, two lesion sites were used for 3D reconstruction. The core of the typical lesion consisted of eosinophilic material associated with reticulin loss, collagen damage including loss of birefringence to fibrous septa, and perilesional portal tracts, including large portal vein branches, but intact peri-lesional hepatic plates. The 3D reconstruction of two histotripsy sites was successful and confirmed the feasibility of this approach to investigate the effects of histotripsy on tissue in detail.

Liver Ultrasound Histotripsy: Novel Analysis of the Histotripsy Site Cell Constituents with Implications for Histotripsy Application in Cell Transplantation and Cancer Therapy

Introduction: Allogenic hepatocyte transplantation is an attractive alternative to whole-organ transplantation, particularly for the treatment of metabolic disorders and acute liver failure. However, the shortage of human donor organs for cell isolation, the low cell yield from decellularisation regimes, and low engraftment rates from portal administration of donor cells have restricted its clinical application. Using ultrasound histotripsy to provide a nidus in the liver for direct cell transplantation offers a new approach to overcoming key limitations in current cell therapy. We have analysed the liver cavity constituents to assess their potential as a site for cell delivery and implantation. Methods: Using human organ retrieval techniques, pig livers were collected from the abattoir and transported in ice-cold storage to the laboratory. Following 2 h of cold storage, the livers were flushed with organ preservation solution and placed on an organ perfusion circuit to maintain viability. Organs were perfused with Soltran™ organ preservation solution via the portal vein at a temperature of 24-30 °C. The perfusion circuit was oxygenated through equilibration with room air. Perfused livers (n=5) were subjected to ultrasound histotripsy, producing a total of 130 lesions. Lesions were generated by applying 50 pulses at 1 Hz pulse repetition frequency and 1% duty cycle using a single element 2 MHz bowl-shaped transducer (Sonic Concepts, H-148). Following histotripsy, a focal liver lesion was produced, which had a liquid centre. The fluid from each lesion was aspirated and cultured in medium (RPMI) at 37 °C in an incubator. Cell cultures were analysed at 1 and 7 days for cell viability and a live-dead assay was performed. The histotripsy sites were excised following aspiration and H&E staining was used to characterise the liver lesions. Cell morphology was determined by histology. Results: Histotripsy created a subcapsular lesion (~5 mm below the liver capsule; size ranging from 3 to 5 mm), which contained a suspension of cells. On average, 61×10⁴ cells per mL were isolated. Hepatocytes were present in the aspirate, were viable at 24 h post isolation and remained viable in culture for up to 1 week, as determined by phalloidin/DAPI cell viability stains. Cultures up to 21 days revealed metabolically active live hepatocyte. Live-dead assays confirmed hepatocyte viability at 1 week (Day 1: 12% to Day 7: 45% live cells; p < 0.0001), which retained metabolic activity and morphology, confirmed on assay and microscopy. Cell Titre-Glo^TM showed a peak metabolic activity at 1 week (average luminescence 24.6 RLU; p < 0.0001) post-culture compared with the control (culture medium alone), reduced to 1/3 of peak level (7.85 RLU) by day 21. Conclusions: Histotripsy of the liver allows isolation and culture of hepatocytes with a high rate of viability after 1 week in culture. Reproducing these findings using human livers may lead to wide clinical applications in cell therapy.

Nuclear factor programming improves stem-cell-derived hepatocyte phenotype

In this issue of Cell Stem Cell, Ma et al. demonstrate that the activation of the nuclear receptor thyroid hormone receptor beta (NR1A2) improves the differentiation status of hepatocyte-like cells derived from human pluripotent stem cells.

Generation of 3D retinal tissue from human pluripotent stem cells using a directed small molecule-based serum-free microwell platform

Retinal degenerative diseases are a leading cause of blindness worldwide with debilitating life-long consequences for the affected individuals. Cell therapy is considered a potential future clinical intervention to restore and preserve sight by replacing lost photoreceptors and/or retinal pigment epithelium. Development of protocols to generate retinal tissue from human pluripotent stem cells (hPSC), reliably and at scale, can provide a platform to generate photoreceptors for cell therapy and to model retinal disease in vitro. Here, we describe an improved differentiation platform to generate retinal organoids from hPSC at scale and free from time-consuming manual microdissection steps. The scale up was achieved using an agarose mould platform enabling generation of uniform self-assembled 3D spheres from dissociated hPSC in microwells. Subsequent retinal differentiation was efficiently achieved via a stepwise differentiation protocol using a number of small molecules. To facilitate clinical translation, xeno-free approaches were developed by substituting Matrigel™ and foetal bovine serum with recombinant laminin and human platelet lysate, respectively. Generated retinal organoids exhibited important features reminiscent of retinal tissue including correct site-specific localisation of proteins involved in phototransduction.

Serum-Free Production of Three-Dimensional Hepatospheres from Pluripotent Stem Cells

Developing renewable human liver tissue from stem cells has been pursued as a potential source of biological material for pharmaceutical and clinical endeavors. At present, two-dimensional differentiation procedures deliver tissue lacking long-term phenotypic and functional stability. Efforts to overcome these limiting factors have led to the development of protocols to generate three-dimensional cellular aggregates. Here we describe a methodology to generate 3D hepatospheres from human pluripotent stem cells using defined and commercially available reagents.

Serum Free Production of Three-dimensional Human Hepatospheres from Pluripotent Stem Cells

The development of renewable sources of liver tissue is required to improve cell-based modelling, and develop human tissue for transplantation. Human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) represent promising sources of human liver spheres. We have developed a serum free and defined method of cellular differentiation to generate three-dimensional human liver spheres formed from human pluripotent stem cells. A potential limitation of the technology is the production of dense spheres with dead material inside. In order to circumvent this, we have employed agarose microwell technology at defined cell densities to control the size of the 3D spheres, preventing the generation of apoptotic and/or necrotic cores.  Notably, the spheres generated by our approach display liver function and stable phenotype, representing a valuable resource for basic and applied scientific research. We believe that our approach could be used as a platform technology to develop further tissues to model and treat human disease and in the future may permit the generation of human tissue with complex tissue architecture.

Three-dimensional cell culture: from evolution to revolution

Recent advances in the isolation of tissue-resident adult stem cells and the identification of inductive factors that efficiently direct differentiation of human pluripotent stem cells along specific lineages have facilitated the development of high-fidelity modelling of several tissues in vitro Many of the novel approaches have employed self-organizing three-dimensional (3D) culturing of organoids, which offer several advantages over conventional two-dimensional platforms. Organoid technologies hold great promise for modelling diseases and predicting the outcome of drug responses in vitro Here, we outline the historical background and some of the recent advances in the field of three-dimensional organoids. We also highlight some of the current limitations of these systems and discuss potential avenues to further benefit biological research using three-dimensional modelling technologies.This article is part of the theme issue 'Designer human tissue: coming to a lab near you'.

3D human liver tissue from pluripotent stem cells displays stable phenotype in vitro and supports compromised liver function in vivo

Liver disease is an escalating global health issue. While liver transplantation is an effective mode of therapy, patient mortality has increased due to the shortage of donor organs. Developing renewable sources of human liver tissue is therefore attractive. Pluripotent stem cell-derived liver tissue represents a potential alternative to cadaver derived hepatocytes and whole organ transplant. At present, two-dimensional differentiation procedures deliver tissue lacking certain functions and long-term stability. Efforts to overcome these limiting factors have led to the building of three-dimensional (3D) cellular aggregates. Although enabling for the field, their widespread application is limited due to their reliance on variable biological components. Our studies focused on the development of 3D liver tissue under defined conditions. In vitro generated 3D tissues exhibited stable phenotype for over 1 year in culture, providing an attractive resource for long-term in vitro studies. Moreover, 3D derived tissue provided critical liver support in two animal models, including immunocompetent recipients. Therefore, we believe that our study provides stable human tissue to better model liver biology 'in the dish', and in the future may permit the support of compromised liver function in humans.

Liver cell therapy: is this the end of the beginning?

The prevalence of liver diseases is increasing globally. Orthotopic liver transplantation is widely used to treat liver disease upon organ failure. The complexity of this procedure and finite numbers of healthy organ donors have prompted research into alternative therapeutic options to treat liver disease. This includes the transplantation of liver cells to promote regeneration. While successful, the routine supply of good quality human liver cells is limited. Therefore, renewable and scalable sources of these cells are sought. Liver progenitor and pluripotent stem cells offer potential cell sources that could be used clinically. This review discusses recent approaches in liver cell transplantation and requirements to improve the process, with the ultimate goal being efficient organ regeneration. We also discuss the potential off-target effects of cell-based therapies, and the advantages and drawbacks of current pre-clinical animal models used to study organ senescence, repopulation and regeneration.

Selection on resilience improves disease resistance and tolerance to infections

Response to infection in animals has 2 main mechanisms: resistance (ability to control pathogen burden) and tolerance (ability to maintain performance given the pathogen burden). Selection on disease resistance and tolerance to infections seems a promising avenue to increase productivity of animals in the presence of disease infections, but it is hampered by a lack of records of pathogen burden of infected animals. Selection on resilience (ability to maintain performance regardless of pathogen burden) may, therefore, be an alternative pragmatic approach, because it does not need records of pathogen burden. Therefore, the aim of this study was to assess response to selection in resistance and tolerance when selecting on resilience compared with direct selection on resistance and tolerance. Monte Carlo simulation was used combined with selection index theory to predict responses to selection. Using EBV for resilience in the absence of records for pathogen burden resulted in favorable responses in resistance and tolerance to infections, with higher responses in tolerance than in resistance. If resistance and tolerance were unfavorably correlated, lower selection responses were obtained, especially in resistance. When the genetic correlation was very unfavorable, the selection response in tolerance became negative. Results showed that lower selection responses in resistance and tolerance were obtained when the frequency of disease outbreaks was 10% rather than 50% of the contemporary groups. The efficiency of selection on EBV for resilience compared with selection on EBV for resistance and tolerance was, however, not affected by the frequency of disease outbreaks. When records on pathogen burden were available, selection responses in resistance, tolerance, and the total breeding goal were 3 to 28%, 66 to 398%, and 2 to 11% higher, respectively, than when using the EBV for resilience, showing a clear benefit of recording pathogen burden. This study shows that selection on resilience is a pragmatic way of increasing disease resistance and tolerance to infections in the absence of records on pathogen burden, but recording pathogen burden would yield higher selection responses in resistance and tolerance.

Genetic variation for farrowing rate in pigs in response to change in photoperiod and ambient temperature

Seasonal infertility is often observed as anestrus and a lower conception rate resulting in a reduced farrowing rate (FR) during late summer and early autumn. This is often regarded as an effect of heat stress; however, we observed a reduction in the FR of sows even after correcting for ambient temperature in our data. Therefore, we added change in photoperiod in the analysis of FR considering its effect on sow fertility. Change in photoperiod was modeled using the cosine of the day of first insemination within a year. On an average, the FR decreased by 2% during early autumn with decreasing daily photoperiod compared with early summer with almost no change in daily photoperiod. It declined 0.2% per degree Celsius of ambient temperature above 19.2°C. This result is a step forward in disentangling the 2 environmental components responsible for seasonal infertility. Our next aim was to estimate the magnitude of genetic variation in FR in response to change in photoperiod and ambient temperature to explore opportunities for selecting pigs to have a constant FR throughout the year. We used reaction norm models to estimate additive genetic variation in response to change in photoperiod and ambient temperature. The results revealed a larger genetic variation at stressful environments when daily photoperiod decreased and ambient temperatures increased above 19.2°C compared with neutral environments. Genetic correlations between stressful environments and nonstressful environments ranged from 0.90 (±0.03) to 0.46 (±0.13) depending on the severity of the stress, indicating changes in expression of FR depending on the environment. The genetic correlation between responses of pigs to changes in photoperiod and to those in ambient temperature were positive, indicating that pigs tolerant to decreasing daily photoperiod are also tolerant to high ambient temperatures. Therefore, selection for tolerance to decreasing daily photoperiod should also increase tolerance to high ambient temperatures or vice versa.

Defined and Scalable Generation of Hepatocyte-like Cells from Human Pluripotent Stem Cells

Human pluripotent stem cells (hPSCs) possess great value for biomedical research. hPSCs can be scaled and differentiated to all cell types found in the human body. The differentiation of hPSCs to human hepatocyte-like cells (HLCs) has been extensively studied, and efficient differentiation protocols have been established. The combination of extracellular matrix and biological stimuli, including growth factors, cytokines, and small molecules, have made it possible to generate HLCs that resemble primary human hepatocytes. However, the majority of procedures still employ undefined components, giving rise to batch-to-batch variation. This serves as a significant barrier to the application of the technology. To tackle this issue, we developed a defined system for hepatocyte differentiation using human recombinant laminins as extracellular matrices in combination with a serum-free differentiation process. Highly efficient hepatocyte specification was achieved, with demonstrated improvements in both HLC function and phenotype. Importantly, this system is easy to scale up using research and GMP-grade hPSC lines promising advances in cell-based modelling and therapies.

Fluid shear stress modulation of hepatocyte-like cell function

Freshly isolated human adult hepatocytes are considered to be the gold standard tool for in vitro studies. However, primary hepatocyte scarcity, cell cycle arrest and the rapid loss of cell phenotype limit their widespread deployment. Human embryonic stem cells and induced pluripotent stem cells provide renewable sources of hepatocyte-like cells (HLCs). Despite the use of various differentiation methodologies, HLCs like primary human hepatocytes exhibit unstable phenotype in culture. It has been shown that the functional capacity can be improved by adding back elements of human physiology, such as cell co-culture or through the use of natural and/or synthetic surfaces. In this study, the effect of fluid shear stress on HLC performance was investigated. We studied two important liver functions, cytochrome P450 drug metabolism and serum protein secretion, in static cultures and those exposed to fluid shear stress. Our study demonstrates that fluid shear stress improved Cyp1A2 activity by approximately fivefold. This was paralleled by an approximate ninefold increase in sensitivity to a drug, primarily metabolised by Cyp2D6. In addition to metabolic capacity, fluid shear stress also improved hepatocyte phenotype with an approximate fourfold reduction in the secretion of a foetal marker, alpha-fetoprotein. We believe these studies highlight the importance of introducing physiologic cues in cell-based models to improve somatic cell phenotype.

Pluripotent stem cell derived hepatocytes: using materials to define cellular differentiation and tissue engineering

Pluripotent stem cell derived liver cells (hepatocytes) represent a promising alternative to primary tissue for biological and clinical applications. To date, most hepatocyte maintenance and differentiation systems have relied upon the use of animal derived components. This serves as a significant barrier to large scale production and application of stem cell derived hepatocytes. Recently, the use of defined biologics has overcome those limitations in two-dimensional monolayer culture. In order to improve the cell phenotype further, three-dimensional culture systems have been employed to better mimic the in vivo situation, drawing upon materials chemistry, engineering and biology. In this review we discuss efforts in the field, to differentiate pluripotent stem cells towards hepatocytes under defined conditions.

Does the risk of metabolic disorders increase among women with polycystic ovary morphology? A population-based study

STUDY QUESTION

Is polycystic ovary morphology (PCOM) associated with metabolic syndrome (MS), insulin resistance (IR) and dyslipidemia?

SUMMARY ANSWER

No associations between PCOM and metabolic disorders were found.

WHAT IS KNOWN ALREADY

Polycystic ovary morphology has a prevalence of 21-63% in healthy women of reproductive age. Results of studies focusing on metabolic abnormalities among females with PCOM, are insufficient and controversial.

STUDY DESIGN, SIZE, DURATION

This was a cross-sectional population-based study from five provinces in Iran. A standard questionnaire was filled out during face-to-face interviews and clinical examinations were done. All study subjects were invited to undergo blood sampling and ultrasonographic assessment.

PARTICIPANTS/MATERIALS, SETTING, METHODS

From a total of 1772 women, 809 participants met the inclusion criteria of this study, i.e. non-pregnant, reproductive-age, ovulatory, normo-androgenic, without hyperprolactinemia/thyroid dysfunction. Participants were divided into two groups; 126 women with PCOM on ultrasound assessment, as the case and 683 women with normal ovarian morphology, as the control groups. The association of PCOM with MS, IR and dyslipidemia were analyzed using logistic regression models, adjusted for confounding variables.

MAIN RESULTS AND THE ROLE OF CHANCE

Mean systolic blood pressure (SBP), high density lipoprotein (HDL) and androstenedione (A4) serum levels of women with PCOM were significantly higher than in the normal group (P = 0.04, 0.05 and 0.008, respectively). Comparison between groups revealed dyslipidemia to be higher among controls. However the results of logistic regression models, after adjustment for possible confounding variables showed that there were no significant association between prevalence of MS, IR and dyslipidemia with PCOM.

LIMITATIONS, REASONS FOR CAUTION

Due to the study being cross-sectional, blood samples were collected only once thus we did not measure serum concentrations of progesterone in the luteal phase, which determines subclinical anovulation. Moreover, due to budget limitations, enzyme immunoassay was used for androgenic measurements while mass spectrometry-based assays have been known as the gold standard method. However we defined our groups very strictly to overcome these limitations.

WIDER IMPLICATIONS OF THE FINDINGS

It seems that biochemical and metabolic characteristics of women with PCOM do not differ significantly to those of normal women. To clarify the association between PCOM and metabolic characteristics, longitudinal studies investigating long-term metabolic disorders among women with PCOM are highly recommended.

STUDY FUNDING/COMPETING INTEREST

No external funding was used for this study. No conflicts of interest are declared.

Estimation of genetic parameters and breeding values across challenged environments to select for robust pigs

Robustness is an important issue in the pig production industry. Since pigs from international breeding organizations have to withstand a variety of environmental challenges, selection of pigs with the inherent ability to sustain their productivity in diverse environments may be an economically feasible approach in the livestock industry. The objective of this study was to estimate genetic parameters and breeding values across different levels of environmental challenge load. The challenge load (CL) was estimated as the reduction in reproductive performance during different weeks of a year using 925,711 farrowing records from farms distributed worldwide. A wide range of levels of challenge, from favorable to unfavorable environments, was observed among farms with high CL values being associated with confirmed situations of unfavorable environment. Genetic parameters and breeding values were estimated in high- and low-challenge environments using a bivariate analysis, as well as across increasing levels of challenge with a random regression model using Legendre polynomials. Although heritability estimates of number of pigs born alive were slightly higher in environments with extreme CL than in those with intermediate levels of CL, the heritabilities of number of piglet losses increased progressively as CL increased. Genetic correlations among environments with different levels of CL suggest that selection in environments with extremes of low or high CL would result in low response to selection. Therefore, selection programs of breeding organizations that are commonly conducted under favorable environments could have low response to selection in commercial farms that have unfavorable environmental conditions. Sows that had experienced high levels of challenge at least once during their productive life were ranked according to their EBV. The selection of pigs using EBV ignoring environmental challenges or on the basis of records from only favorable environments resulted in a sharp decline in productivity as the level of challenge increased. In contrast, selection using the random regression approach resulted in limited change in productivity with increasing levels of challenge. Hence, we demonstrate that the use of a quantitative measure of environmental CL and a random regression approach can be comprehensively combined for genetic selection of pigs with enhanced ability to maintain high productivity in harsh environments.

In Vivo Assessment of Bone Regeneration in Alginate/Bone ECM Hydrogels with Incorporated Skeletal Stem Cells and Single Growth Factors

The current study has investigated the use of decellularised, demineralised bone extracellular matrix (ECM) hydrogel constructs for in vivo tissue mineralisation and bone formation. Stro-1-enriched human bone marrow stromal cells were incorporated together with select growth factors including VEGF, TGF-β3, BMP-2, PTHrP and VitD3, to augment bone formation, and mixed with alginate for structural support. Growth factors were delivered through fast (non-osteogenic factors) and slow (osteogenic factors) release PLGA microparticles. Constructs of 5 mm length were implanted in vivo for 28 days within mice. Dense tissue assessed by micro-CT correlated with histologically assessed mineralised bone formation in all constructs. Exogenous growth factor addition did not enhance bone formation further compared to alginate/bone ECM (ALG/ECM) hydrogels alone. UV irradiation reduced bone formation through degradation of intrinsic growth factors within the bone ECM component and possibly also ECM cross-linking. BMP-2 and VitD3 rescued osteogenic induction. ALG/ECM hydrogels appeared highly osteoinductive and delivery of angiogenic or chondrogenic growth factors led to altered bone formation. All constructs demonstrated extensive host tissue invasion and vascularisation aiding integration and implant longevity. The proposed hydrogel system functioned without the need for growth factor incorporation or an exogenous inducible cell source. Optimal growth factor concentrations and spatiotemporal release profiles require further assessment, as the bone ECM component may suffer batch variability between donor materials. In summary, ALG/ECM hydrogels provide a versatile biomaterial scaffold for utilisation within regenerative medicine which may be tailored, ultimately, to form the tissue of choice through incorporation of select growth factors.

Polyurethane: Stable Cell Phenotype Requires Plasticity: Polymer Supported Directed Differentiation Reveals a Unique Gene Signature Predicting Stable Hepatocyte Performance (Adv. Healthcare Mater. 12/2015)

One major obstacle to the routine deployment of stem cell-derived cells is their instability in culture. On page 1820 David C. Hay and co-workers describe the use of a synthetic polymer surface. The image shows stem cell-derived hepatocytes replated on this polyurethane surface. Importantly the cells express Zonal Occludin (green stain) at the cell surface, which indicates that the cells display elements of polarization. The blue stain is DAPI, which demarks the nucleus.

Polymer Supported Directed Differentiation Reveals a Unique Gene Signature Predicting Stable Hepatocyte Performance

In theory, pluripotent stem cells can give rise to all somatic cell types found in the human body. The ability to generate renewable sources of human cells has enormous potential to improve human health and wealth. One major obstacle to the routine deployment of stem cell-derived cells is their instability in culture. To tackle this issue a synthetic polymer surface is used.

A thermoresponsive and magnetic colloid for 3D cell expansion and reconfiguration

A dual thermoresponsive and magnetic colloidal gel matrix is described for enhanced stem-cell culture. The combined properties of the material allow enzyme-free passaging and expansion of mesenchymal stem cells, as well as isolation of cells postculture by the simple process of lowering the temperature and applying an external magnetic field. The colloidal gel can be reconfigured with thermal and magnetic stimuli to allow patterning of cells in discrete zones and to control movement of cells within the porous matrix during culture.

Tissue engineered bone using select growth factors: A comprehensive review of animal studies and clinical translation studies in man

There is a growing socio-economic need for effective strategies to repair damaged bone resulting from disease, trauma and surgical intervention. Bone tissue engineering has received substantial investment over the last few decades as a result. A multitude of studies have sought to examine the efficacy of multiple growth factors, delivery systems and biomaterials within in vivo animal models for the repair of critical-sized bone defects. Defect repair requires recapitulation of in vivo signalling cascades, including osteogenesis, chondrogenesis and angiogenesis, in an orchestrated spatiotemporal manner. Strategies to drive parallel, synergistic and consecutive signalling of factors including BMP-2, BMP-7/OP-1, FGF, PDGF, PTH, PTHrP, TGF-β3, VEGF and Wnts have demonstrated improved bone healing within animal models. Enhanced bone repair has also been demonstrated in the clinic following European Medicines Agency and Food and Drug Administration approval of BMP-2, BMP-7/OP-1, PDGF, PTH and PTHrP. The current review assesses the in vivo and clinical data surrounding the application of growth factors for bone regeneration. This review has examined data published between 1965 and 2013. All bone tissue engineering studies investigating in vivo response of the growth factors listed above, or combinations thereof, utilising animal models or human trials were included. All studies were compiled from PubMed-NCBI using search terms including 'growth factor name', 'in vivo', 'model/animal', 'human', and 'bone tissue engineering'. Focus is drawn to the in vivo success of osteoinductive growth factors incorporated within material implants both in animals and humans, and identifies the unmet challenges within the skeletal regenerative area.

Evaluation of skeletal tissue repair, part 1: assessment of novel growth-factor-releasing hydrogels in an ex vivo chick femur defect model

Current clinical treatments for skeletal conditions resulting in large-scale bone loss include autograft or allograft, both of which have limited effectiveness. In seeking to address bone regeneration, several tissue engineering strategies have come to the fore, including the development of growth factor releasing technologies and appropriate animal models to evaluate repair. Ex vivo models represent a promising alternative to simple in vitro systems or complex, ethically challenging in vivo models. We have developed an ex vivo culture system of whole embryonic chick femora, adapted in this study as a critical size defect model to investigate the effects of novel bone extracellular matrix (bECM) hydrogel scaffolds containing spatio-temporal growth factor-releasing microparticles and skeletal stem cells on bone regeneration, to develop a viable alternative treatment for skeletal degeneration. Alginate/bECM hydrogels combined with poly (d,l-lactic-co-glycolic acid) (PDLLGA)/triblock copolymer (10-30% PDLLGA-PEG-PDLLGA) microparticles releasing VEGF, TGF-β3 or BMP-2 were placed, with human adult Stro-1+ bone marrow stromal cells, into 2mm central segmental defects in embryonic chick femurs. Alginate/bECM hydrogels loaded with HSA/VEGF or HSA/TGF-β3 demonstrated a cartilage-like phenotype, with minimal collagen I deposition, comparable to HSA-only control hydrogels. The addition of BMP-2 releasing microparticles resulted in enhanced structured bone matrix formation, evidenced by increased Sirius red-stained matrix and collagen expression within hydrogels. This study demonstrates delivery of bioactive growth factors from a novel alginate/bECM hydrogel to augment skeletal tissue formation and the use of an organotypic chick femur defect culture system as a high-throughput test model for scaffold/cell/growth factor therapies for regenerative medicine.

Evaluation of skeletal tissue repair, part 2: enhancement of skeletal tissue repair through dual-growth-factor-releasing hydrogels within an ex vivo chick femur defect model

There is an unmet need for improved, effective tissue engineering strategies to replace or repair bone damaged through disease or injury. Recent research has focused on developing biomaterial scaffolds capable of spatially and temporally releasing combinations of bioactive growth factors, rather than individual molecules, to recapitulate repair pathways present in vivo. We have developed an ex vivo embryonic chick femur critical size defect model and applied the model in the study of novel extracellular matrix (ECM) hydrogel scaffolds containing spatio-temporal combinatorial growth factor-releasing microparticles and skeletal stem cells for bone regeneration. Alginate/bovine bone ECM (bECM) hydrogels combined with poly(d,l-lactic-co-glycolic acid) (PDLLGA)/triblock copolymer (10-30% PDLLGA-PEG-PLDLGA) microparticles releasing dual combinations of vascular endothelial growth factor (VEGF), chondrogenic transforming growth factor beta 3 (TGF-β3) and the bone morphogenetic protein BMP2, with human adult Stro-1+bone marrow stromal cells (HBMSCs), were placed into 2mm central segmental defects in embryonic day 11 chick femurs and organotypically cultured. Hydrogels loaded with VEGF combinations induced host cell migration and type I collagen deposition. Combinations of TGF-β3/BMP2, particularly with Stro-1+HBMSCs, induced significant formation of structured bone matrix, evidenced by increased Sirius red-stained matrix together with collagen expression demonstrating birefringent alignment within hydrogels. This study demonstrates the successful use of the chick femur organotypic culture system as a high-throughput test model for scaffold/cell/growth factor therapies in regenerative medicine. Temporal release of dual growth factors, combined with enriched Stro-1+HBMSCs, improved the formation of a highly structured bone matrix compared to single release modalities. These studies highlight the potential of a unique alginate/bECM hydrogel dual growth factor release platform for bone repair.

Remotely Activated Mechanotransduction via Magnetic Nanoparticles Promotes Mineralization Synergistically With Bone Morphogenetic Protein 2: Applications for Injectable Cell Therapy

Bone requires dynamic mechanical stimulation to form and maintain functional tissue, yet mechanical stimuli are often lacking in many therapeutic approaches for bone regeneration. Magnetic nanoparticles provide a method for delivering these stimuli by directly targeting cell-surface mechanosensors and transducing forces from an external magnetic field, resulting in remotely controllable mechanotransduction. In this investigation, functionalized magnetic nanoparticles were attached to either the mechanically gated TREK1 K+ channel or the (integrin) RGD-binding domains of human mesenchymal stem cells. These cells were microinjected into an ex vivo chick fetal femur (embryonic day 11) that was cultured organotypically in vitro as a model for endochondral bone formation. An oscillating 25-mT magnetic field delivering a force of 4 pN per nanoparticle directly against the mechanoreceptor induced mechanotransduction in the injected mesenchymal stem cells. It was found that cells that received mechanical stimuli via the nanoparticles mineralized the epiphyseal injection site more extensively than unlabeled control cells. The nanoparticle-tagged cells were also seeded into collagen hydrogels to evaluate osteogenesis in tissue-engineered constructs: in this case, inducing mechanotransduction by targeting TREK1 resulted in a 2.4-fold increase in mineralization and significant increases in matrix density. In both models, the combination of mechanical stimulation and sustained release of bone morphogenetic protein 2 (BMP2) from polymer microspheres showed a significant additive effect on mineralization, increasing the effectiveness of BMP2 delivery and demonstrating that nanoparticle-mediated mechanotransduction can be used synergistically with pharmacological approaches for orthopedic tissue engineering to maximize bone formation.

A cross-sectional study of the seroprevalence and flock-level factors associated with ovine and caprine brucellosis in southeastern Iran

This cross-sectional study was conducted to estimate seroprevalence and to identify flock-level factors associated with seropositivity to brucellosis in small ruminants in Kerman province, southeastern Iran. In October-November 2011, serum samples were randomly collected from 1767 sheep and 1233 goats, older than 18 months, from 300 flocks. The sera were initially screened for the presence of anti-Brucella antibodies using the Rose-Bengal test; those found to be positive were then examined by Wright and 2-mercaptoethanol Brucella agglutination tests. A questionnaire was used to collect data on flock-level factors likely associated with the within flock seroprevalence of brucellosis. The associations were statistically evaluated for significance in multivariable logistic models. Sixty three flocks (21.00%; 95% CI: 16.80-26.60) had at least one seropositive animal. The mean within-flock seroprevalence was 3.10% (95% CI: 2.60-3.90). The presence of newly purchased animals (OR=3.42; 95% CI: 1.35-8.65) was significantly associated with seropositivity. Our findings highlight the role of animal movement among flocks in the epidemiology of brucellosis in this region. Thus, a control program for brucellosis in the region is suggested to impose appropriate restrictions on animal trade and improve knowledge of livestock owners about quarantine principles for newly purchased animals.

Surface engineering of synthetic polymer materials for tissue engineering and regenerative medicine applications

When using polymer materials as scaffolds for tissue engineering or regenerative medicine applications the initial, and often lasting, interaction between cells and the material areviasurfaces.

Developmental effects of cannabinoids on zebrafish larvae

Cannabinoids are natural or synthetic compounds related chemically to (-)-(6aR,10aR)-6,6,9-trimethyl-3-pentyl-6a,7,8,10a-tetrahydro-6H-benzo[c]chromen-1-ol (Δ(9)-THC), the principle psychotropic constituent of the hemp plant, Cannabis sativa L. Here we examine the effects of the cannabinoids Δ(9)-THC, (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo [1,2,3-de]-1,4-benzoxazin-6-yl]-1-napthalenylmethanone and 2-[(1R,2R,5R)-5-hydroxy-2-(3-hydroxypropyl) cyclohexyl]-5-(2-methyloctan-2-yl)phenol, and the cannabinoid antagonist (AM 251). Exposures were either acute (1-12-h exposure at 108 hours of postfertilization [hpf]) or chronic (96-h exposure starting at 24 hpf). Geometric range finding was used to determine the experimental concentrations. The concentration of the chemical that kills 50% of the test animals in a given time (LC50) was determined based on cumulative mortality at 5 days of postfertilization. At day 5, behavioral analysis (visual motor response test) was carried out in which movement of individual larvae was analysed using automated video-tracking. With acute exposure, embryos showed a biphasic response to the dark challenge with all three cannabinoids tested. This response consisted of stimulation of the locomotor activity at low concentrations, suppression at high doses. With chronic exposure, embryos habituated to the effects of all three cannabinoids when assayed with the dark challenge phase. Further, the excitation was ameliorated when the antagonist AM 251 was coadministered with the cannabinoid. When AM 251 was administered on its own (chronically or acutely), the locomotor activity was suppressed at high concentrations. We examined the embryos for a range of malformations after chronic exposure to cannabinoid. Only Δ(9)-THC was associated with a significant increase in malformations at 5d (yolk sac and pericardial edema, bent tail/body axis). We conclude that cannabinoids have behavioral effects in zebrafish that are comparable to some of those reported in the literature for mammals. In particular, the acute exposure response resembles behavioral effects reported for adult rodents. Our data are consistent with these behavioral effects being mediated, at least in part, by the CB1 receptor.

Transient serum exposure regimes to support dual differentiation of human mesenchymal stem cells

Human mesenchymal stem cells (MSCs), which can generate both osteoblasts and chondrocytes, represent an ideal resource for orthopaedic repair using tissue-engineering approaches. One major difficulty for the development of osteochondral constructs using undifferentiated MSCs is that serum is typically used in culture protocols to promote differentiation of the osteogenic component, whereas existing chondrogenic differentiation protocols rely on the use of serum-free conditions. In order to define conditions which could be compatible with both chondrogenic and osteogenic differentiation in a single bioreactor, we have analysed the efficiency of new biphasic differentiation regimes based on transient serum exposure followed by serum-free treatment. MSC differentiation was assessed either in serum-free medium or with a range of transient exposure to serum, and compared to continuous serum-containing treatment. Although osteogenic differentation was not supported in the complete absence of serum, marker expression and extensive mineralization analyses established that 5 days of transient exposure triggered a level of differentiation comparable to that observed when serum was present throughout. This initial phase of serum exposure was further shown to support the successful chondrogenic differentiation of MSCs, comparable to controls maintained in serum-free conditions throughout. This study indicates that a culture based on temporal serum exposure followed by serum-free treatment is compatible with both osteogenic and chondrogenic differentiation of MSCs. These results will allow the development of novel strategies for osteochondral tissue engineering approaches using MSCs for regenerative medicine.

Report on 2nd Royan Institute International Summer School on developmental biology and stem cells Tehran, Iran, 17-22nd July 2011

The 2nd Royan Institute International Summer School was built around the topic of stem cells and grounding in the discipline of developmental biology. The meeting provided not only direct transfer of technical and intellectual information, the normal process in scientific meetings, but was also a forum for the exchange of personal ideas of science as a creative pursuit. This summer school introduced aspiring young Iranian scientists to international researchers and exposed the latter to a rich culture that highly values learning and education, attested by the confident, intelligent young men and women who asked probing questions and who were eager to participate in the workshops. Hossein Baharvand's dedication and passion for science have led to an impressive record of national and international peer-reviewed publications and an increasing number of students who pursue science in Iran, and shows how the right people can create an environment where good science, good science education and motivation will flourish. This report summarizes some of the activities of the workshop in the Royan Institute and the impressions of the visiting scientists in the wider context of the scientific and cultural heritage of Iran.

Differences in the pattern and regulation of mineral deposition in human cell lines of osteogenic and non-osteogenic origin

Bone marrow-derived mesenchymal stem cells (MSCs) are widely used as a cellular model of bone formation, and can mineralize in vitro in response to osteogenic medium (OM). It is unclear, however, whether this property is specific to cells of mesenchymal origin. We analysed the OM response in 3 non-osteogenic lines, HEK293, HeLa and NTera, compared to MSCs. Whereas HEK293 cells failed to respond to OM conditions, the 2 carcinoma-derived lines NTera and HeLa deposited a calcium phosphate mineral comparable to that present in MSC cultures. However, unlike MSCs, HeLa and NTera cultures did so in the absence of dexamethasone. This discrepancy was confirmed, as bone morphogenetic protein inhibition obliterated the OM response in MSCs but not in HeLa or NTera, indicating that these 2 models can deposit mineral through a mechanism independent of established dexamethasone or bone morphogenetic protein signalling.

Hydroxylation and further oxidation of delta9-tetrahydrocannabinol by alkane-degrading bacteria

The microbial biotransformation of Delta(9)-tetrahydrocannabinol was investigated using a collection of 206 alkane-degrading strains. Fifteen percent of these strains, mainly gram-positive strains from the genera Rhodococcus, Mycobacterium, Gordonia, and Dietzia, yielded more-polar derivatives. Eight derivatives were produced on a mg scale, isolated, and purified, and their chemical structures were elucidated with the use of liquid chromatography-mass spectrometry, (1)H-nuclear magnetic resonance (1H-NMR), and two-dimensional NMR (1H-1H correlation spectroscopy and heteronuclear multiple bond coherence). All eight biotransformation products possessed modified alkyl chains, with hydroxy, carboxy, and ester functionalities. In a number of strains, beta-oxidation of the initially formed C5 carboxylic acid led to the formation of a carboxylic acid lacking two methylene groups.

The chick embryo: hatching a model for contemporary biomedical research

Animal models play a crucial role in fundamental and medical research. Progress in the fields of drug discovery, regenerative medicine and cancer research among others are heavily dependent on in vivo models to validate in vitro observations, and develop new therapeutic approaches. However, conventional rodent and large animal experiments face ethical, practical and technical issues that limit their usage. The chick embryo represents an accessible and economical in vivo model, which has long been used in developmental biology, gene expression analysis and loss/gain of function experiments. It is also an established model for tissue/cell transplantation, and because of its lack of immune system in early development, the chick embryo is increasingly recognised as a model of choice for mammalian biology with new applications for stem cell and cancer research. Here, we review novel applications of the chick embryo model, and discuss future developments of this in vivo model for biomedical research.

Cannabis tea revisited: a systematic evaluation of the cannabinoid composition of cannabis tea

Cannabis is one of the oldest known medicinal plants, and a large variety of biological activities have been described. The main constituents, the cannabinoids, are thought to be most important for these activities. Although smoking of cannabis is by far the most common way of consumption, a significant part of medicinal users consume it in the form of a tea. However, not much is known about the composition of cannabis tea, or the effect of different parameters during preparation, handling or storage. In this study we used the high-grade cannabis available in Dutch pharmacies to study the cannabinoid composition of tea under standardized and quantitative conditions. Experimental conditions were systematically varied in order to mimic the possible variations made by medicinal users. During analysis there was a specific focus on the cannabinoid tetrahydrocannabinol and its acidic precursor, tetrahydrocannabinolic acid. Also the role of non-psychoactive cannabinoids as components of cannabis tea are discussed. The results obtained in this study provide a clear quantitative insight in the phytochemistry of cannabis tea preparation and can contribute to a better appreciation of this mode of cannabis administration.

Passionflower in the treatment of generalized anxiety: a pilot double-blind randomized controlled trial with oxazepam

OBJECTIVE

Passionflower (Passiflora incarnata) is a folk remedy for anxiety. A double-blind randomized trial compared the efficacy of Passiflora incarnata extract with oxazepam in the treatment of generalized anxiety disorder.

METHODS

The study was performed on 36 out-patients diagnosed with GAD using DSM IV criteria. Patients were allocated in a random fashion: 18 to the Passiflora extract 45 drops/day plus placebo tablet group, and 18 to oxazepam 30 mg/day plus placebo drops for a 4-week trial.

RESULTS

Passiflora extract and oxazepam were effective in the treatment of generalized anxiety disorder. No significant difference was observed between the two protocols at the end of trial. Oxazepam showed a rapid onset of action. On the other hand, significantly more problems relating to impairment of job performance were encountered with subjects on oxazepam.

CONCLUSION

The results suggest that Passiflora extract is an effective drug for the management of generalized anxiety disorder, and the low incidence of impairment of job performance with Passiflora extract compared to oxazepam is an advantage. A large-scale trial is justified.