Cellularizing hydrogel-based scaffolds to repair bone tissue: How to create a physiologically relevant micro-environment?

Tissue engineering is a promising alternative to autografts or allografts for the regeneration of large bone defects. Cell-free biomaterials with different degrees of sophistication can be used for several therapeutic indications, to stimulate bone repair by the host tissue. However, when osteoprogenitors are not available in the damaged tissue, exogenous cells with an osteoblast differentiation potential must be provided. These cells should have the capacity to colonize the defect and to participate in the building of new bone tissue. To achieve this goal, cells must survive, remain in the defect site, eventually proliferate, and differentiate into mature osteoblasts. A critical issue for these engrafted cells is to be fed by oxygen and nutrients: the transient absence of a vascular network upon implantation is a major challenge for cells to survive in the site of implantation, and different strategies can be followed to promote cell survival under poor oxygen and nutrient supply and to promote rapid vascularization of the defect area. These strategies involve the use of scaffolds designed to create the appropriate micro-environment for cells to survive, proliferate, and differentiate in vitro and in vivo. Hydrogels are an eclectic class of materials that can be easily cellularized and provide effective, minimally invasive approaches to fill bone defects and favor bone tissue regeneration. Furthermore, by playing on their composition and processing, it is possible to obtain biocompatible systems with adequate chemical, biological, and mechanical properties. However, only a good combination of scaffold and cells, possibly with the aid of incorporated growth factors, can lead to successful results in bone regeneration. This review presents the strategies used to design cellularized hydrogel-based systems for bone regeneration, identifying the key parameters of the many different micro-environments created within hydrogels.

Adipose-Derived Cell Transplantation in Systemic Sclerosis: State of the Art and Future Perspectives

Systemic sclerosis (SSc) is one of the most complex connective tissue diseases. Although significant progress in the knowledge of pathogenic mechanisms and timely diagnosis, therapeutic options remain limited. The attempt to find new treatments for SSc has led researchers to investigate the potential of cellular therapies using autologous and allogeneic stem cells. Multipotent mesenchymal stromal cells (MSCs) are considered an attractive candidate for cell-based therapies. MSCs comprise a heterogeneous population of cells with multilineage differentiation potential that are preferentially able to home to the sites of damage, and secrete various cytokines and growth factors that can have immunomodulatory, angiogenic, anti-inflammatory and anti-apoptotic effects. MSCs from bone-marrow have been first extensively characterized. Adipose tissue represents an additional abundant and accessible source of stem cells. Compared with BM-MSCs, adipose-derived stromal/stem cells (ASCs) offer several advantages, including ease of isolation, less donor morbidity, relative abundance, and rapidity of expansion. For all these reasons, at present ASCs are one of the most attractive and promising sources of adult stem cells for cell therapy, finding a field of application in the treatment of SSc, too. This review will focus on the current applications and possible future perspectives of adipose tissue-cell therapies in SSc.

Translational Prospects and Challenges in Human Induced Pluripotent Stem Cell Research in Drug Discovery

Despite continuous efforts to improve the process of drug discovery and development, achieving success at the clinical stage remains challenging because of a persistent translational gap between the preclinical and clinical settings. Under these circumstances, the discovery of human induced pluripotent stem (iPS) cells has brought new hope to the drug discovery field because they enable scientists to humanize a variety of pharmacological and toxicological models in vitro. The availability of human iPS cell-derived cells, particularly as an alternative for difficult-to-access tissues and organs, is increasing steadily; however, their use in the field of translational medicine remains challenging. Biomarkers are an essential part of the translational effort to shift new discoveries from bench to bedside as they provide a measurable indicator with which to evaluate pharmacological and toxicological effects in both the preclinical and clinical settings. In general, during the preclinical stage of the drug development process, in vitro models that are established to recapitulate human diseases are validated by using a set of biomarkers; however, their translatability to a clinical setting remains problematic. This review provides an overview of current strategies for human iPS cell-based drug discovery from the perspective of translational research, and discusses the importance of early consideration of clinically relevant biomarkers.

Mesenchymal stem cells as therapeutic target of biophysical stimulation for the treatment of musculoskeletal disorders

BACKGROUND

Musculoskeletal disorders are regarded as a major cause of worldwide morbidity and disability, and they result in huge costs for national health care systems. Traditional therapies frequently turned out to be poorly effective in treating bone, cartilage, and tendon disorders or joint degeneration. As a consequence, the development of novel biological therapies that can treat more effectively these conditions should be the highest priority in regenerative medicine. Mesenchymal stem cells (MSCs) represent one of the most promising tools in musculoskeletal tissue regenerative medicine, thanks to their proliferation and differentiation potential and their immunomodulatory and trophic ability. Indeed, MSC-based approaches have been proposed for the treatment of almost all orthopedic conditions, starting from different cell sources, alone or in combination with scaffolds and growth factors, and in one-step or two-step procedures. While all these approaches would require cell harvesting and transplantation, the possibility to stimulate the endogenous MSCs to enhance their tissue homeostasis activity represents a less-invasive and cost-effective therapeutic strategy. Nowadays, the role of tissue-specific resident stem cells as possible therapeutic target in degenerative pathologies is underinvestigated. Biophysical stimulations, and in particular extracorporeal shock waves treatment and pulsed electromagnetic fields, are able to induce proliferation and support differentiation of MSCs from different origins and affect their paracrine production of growth factors and cytokines.

SHORT CONCLUSIONS

The present review reports the attempts to exploit the resident stem cell potential in musculoskeletal pathologies, highlighting the role of MSCs as therapeutic target of currently applied biophysical treatments.

Potential of Induced Pluripotent Stem Cells (iPSCs) for Treating Age-Related Macular Degeneration (AMD)

The field of stem cell biology has rapidly evolved in the last few decades. In the area of regenerative medicine, clinical applications using stem cells hold the potential to be a powerful tool in the treatment of a wide variety of diseases, in particular, disorders of the eye. Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are promising technologies that can potentially provide an unlimited source of cells for cell replacement therapy in the treatment of retinal degenerative disorders such as age-related macular degeneration (AMD), Stargardt disease, and other disorders. ESCs and iPSCs have been used to generate retinal pigment epithelium (RPE) cells and their functional behavior has been tested in vitro and in vivo in animal models. Additionally, iPSC-derived RPE cells provide an autologous source of cells for therapeutic use, as well as allow for novel approaches in disease modeling and drug development platforms. Clinical trials are currently testing the safety and efficacy of these cells in patients with AMD. In this review, the current status of iPSC disease modeling of AMD is discussed, as well as the challenges and potential of this technology as a viable option for cell replacement therapy in retinal degeneration.

Long-term follow-up after autologous adipose-derived stromal vascular fraction injection into fingers in systemic sclerosis patients

INTRODUCTION

Hand involvement confers a substantial handicap in work and daily activities in patients with Systemic sclerosis (SSc). Autologous adipose-derived stromal vascular fraction is as an easily accessible source of cells with regenerative effects. We previously performed a phase I open-label clinical trial (NTC01813279) assessing the safety of subcutaneous injection of autologous adipose-derived stromal vascular fraction. Six and 12-month data have been reported. As patients were followed in our medical centre, we report their longer-term outcome beyond the end of the trial.

PATIENTS AND METHOD

Twelve females, mean age 54.5±10.3 years, initially enrolled in the clinical trial were assessed during a scheduled medical care, which took place between 22 and 30months after treatment.

RESULTS

Multiple patient-reported outcomes showed sustained improvement, in comparison with the assessment performed just before surgery: 62.5% in the Cochin Hand Function Scale, 51.1% in the Scleroderma Health Assessment Questionnaire, 33.1% in hand pain, and 88.3% in the Raynaud Condition Score. A decrease in the number of digital ulcers number was noted. Mobility, strength and fibrosis of the hand also showed improvement. None of the 8 patients who had previously received iloprost infusion required new infusion.

CONCLUSION

Despite the limits of an open label study, the data are in favour of the long-term safety of the adipose-derived stromal vascular fraction injection. Two randomized double blind, placebo-controlled trials of this therapeutic agent are ongoing in the USA (NCT02396238) and in France (NCT02558543) and will help determine the place of this innovative therapy for SSc patients.

Regenerative Medicine: lessons from Mother Nature

Regenerative medicine strategies for the restoration of functional tissue have evolved from the concept of ex vivo creation of engineered tissue toward the broader concept of in vivo induction of functional tissue reconstruction. Multidisciplinary approaches are being investigated to achieve this goal using evolutionarily conserved principles of stem cell biology, developmental biology and immunology, current methods of engineering and medicine. This evolution from ex vivo tissue engineering to the manipulation of fundamental in vivo tenets of development and regeneration has the potential to capitalize upon the incredibly complex and only partially understood ability of cells to adapt, proliferate, self-organize and differentiate into functional tissue.

[Cell therapies for cardiopathies: the shift of paradigms]

Heart failure is a major concern for public health systems, and several approaches of cellular therapy are being investigated with the goal of improving the function of these failing hearts. Many cell types have been used (skeletal myoblasts, hematopoietic, endothelial or mesenchymal progenitors, cardiac cells…), most often in the indication of post-ischemic heart failure rather than in the indication of genetic dilated cardiomyopathy. It is easier, indeed, to target a restricted area than the whole myocardium. Several clinical trials have reported slight but encouraging functional benefits, but their interpretations were frequently limited by the small sizes of cohorts, and by the biological variabilities inherent to the patients status and to the biology of the cells. These trials also shed light on unexpected mechanisms of action of the cells, which are changing the concepts and methodologies of the studies. The functional benefits observed would be due, indeed, to the secretion of trophic factors by the cells, instead of their true structural and mechanical integration within the myocardial tissue. Accordingly, the new generations of clinical trials aim at improving the size and homogeneity of the patient cohorts to increase the statistical power. On the other hand, several studies are associating or conditionning cells with biomaterials or cocktails of cytokines to improve their survival and their biological efficacy. In parallel, bio-engineering investigates several ways to support cells in vitro and in vivo, to sustain the architectural structure of the failing myocardium, to produce ex vivo some true substitutive cardiac tissue, or to purely replace the cells by their active secreted products. Several therapeutic devices should emerge from these researches, and the choice of their respective use will be ultimately guided by the medical indication.

New experimental models of the blood-brain barrier for CNS drug discovery

INTRODUCTION

The blood-brain barrier (BBB) is a dynamic biological interface which actively controls the passage of substances between the blood and the central nervous system (CNS). From a biological and functional standpoint, the BBB plays a crucial role in maintaining brain homeostasis inasmuch that deterioration of BBB functions are prodromal to many CNS disorders. Conversely, the BBB hinders the delivery of drugs targeting the brain to treat a variety of neurological diseases. Area covered: This article reviews recent technological improvements and innovation in the field of BBB modeling including static and dynamic cell-based platforms, microfluidic systems and the use of stem cells and 3D printing technologies. Additionally, the authors laid out a roadmap for the integration of microfluidics and stem cell biology as a holistic approach for the development of novel in vitro BBB platforms. Expert opinion: Development of effective CNS drugs has been hindered by the lack of reliable strategies to mimic the BBB and cerebrovascular impairments in vitro. Technological advancements in BBB modeling have fostered the development of highly integrative and quasi- physiological in vitro platforms to support the process of drug discovery. These advanced in vitro tools are likely to further current understanding of the cerebrovascular modulatory mechanisms.

Laurus nobilis, Zingiber officinale and Anethum graveolens Essential Oils: Composition, Antioxidant and Antibacterial Activities against Bacteria Isolated from Fish and Shellfish

Several bacterial strains were isolated from wild and reared fish and shellfish. The identification of these strains showed the dominance of the Aeromonas hydrophila species in all seafood samples, followed by Staphylococcus spp., Vibrio alginolyticus, Enterobacter cloacae, Klebsiella ornithinolytica, Klebsiella oxytoca and Serratia odorifera. The isolates were studied for their ability to produce exoenzymes and biofilms. The chemical composition of the essential oils from Laurus nobilis leaves, Zingiber officinale rhizomes and Anethum graveolens aerial parts was studied by GC and GC/MS. The essential oils' antioxidant and antibacterial activities against the isolated microorganisms were studied. Low concentrations of the three essential oils were needed to inhibit the growth of the selected bacteria and the lowest MBCs values were obtained for the laurel essential oil. The selected essential oils can be used as a good natural preservative in fish food due to their antioxidant and antibacterial activities.

Bone regeneration in mandibular fractures after the application of autologous mesenchymal stem cells, a randomized clinical trial

BACKGROUND/AIM

Facial injury in adults can commonly result in fractures of the mandible. Autologous mesenchymal stem cells (AMSCs) transplantation is proposed as an alternative to conventional graft treatment to improve bone regeneration. The aim was to evaluate the effectiveness of AMSCs application in mandibular fractures to reduce regeneration time and increase bone quality.

MATERIALS AND METHODS

This study was a single-blind controlled clinical trial conducted in patients with mandibular angle fractures. Patients were divided into two groups: study group fracture reduction plus application of AMSCs and control group only fracture reduction. AMSCs were obtained from adipose tissue 24 h before the procedure. Intensity and density were evaluated in normal bone and fractured bone at 4 and 12 weeks after surgery using panoramic radiography and computed tomography.

RESULTS

A total of 20 patients, 10 in each group, were included. The study group had a mean age of 31.2 ± 6.3 years, and the control group mean age was 29.7 ± 7.2 years. All patients were male. Bone quality measured in grey levels at week 4 was 108.82 ± 3.4 vs 93.92 ± 2.6 (P = 0.000) using panoramic radiography and 123 ± 4.53 vs 99.72 ± 5.72 (P = 0.000) using computed tomography. At week 12, the measurements were 153.53 ± 1.83 vs 101.81 ± 4.83 (P = 0.000) using panoramic radiography and 165.4 ± 4.2 vs 112.9 ± 2.0 (P = 0.000) using tomography in the study and control groups, respectively.

CONCLUSION

Similar ossification values were obtained after 4 weeks when the use of AMSCs was compared to simple fracture reduction. However, after 12 weeks, the AMSCs group had a 36.48% higher ossification rate.

Proteomics of Skeletal Muscle: Focus on Insulin Resistance and Exercise Biology

Skeletal muscle is the largest tissue in the human body and plays an important role in locomotion and whole body metabolism. It accounts for ~80% of insulin stimulated glucose disposal. Skeletal muscle insulin resistance, a primary feature of Type 2 diabetes, is caused by a decreased ability of muscle to respond to circulating insulin. Physical exercise improves insulin sensitivity and whole body metabolism and remains one of the most promising interventions for the prevention of Type 2 diabetes. Insulin resistance and exercise adaptations in skeletal muscle might be a cause, or consequence, of altered protein expressions profiles and/or their posttranslational modifications (PTMs). Mass spectrometry (MS)-based proteomics offer enormous promise for investigating the molecular mechanisms underlying skeletal muscle insulin resistance and exercise-induced adaptation; however, skeletal muscle proteomics are challenging. This review describes the technical limitations of skeletal muscle proteomics as well as emerging developments in proteomics workflow with respect to samples preparation, liquid chromatography (LC), MS and computational analysis. These technologies have not yet been fully exploited in the field of skeletal muscle proteomics. Future studies that involve state-of-the-art proteomics technology will broaden our understanding of exercise-induced adaptations as well as molecular pathogenesis of insulin resistance. This could lead to the identification of new therapeutic targets.