Mobilizing Endogenous Progenitor Cells Using pSDF1α-Activated Scaffolds Accelerates Angiogenesis and Bone Repair in Critical-Sized Bone Defects.

Mobilizing endogenous progenitor cells to repair damaged tissue in situ has the potential to revolutionize the field of regenerative medicine, while the early establishment of a vascular network will ensure survival of newly generated tissue. In this study, a gene-activated scaffold containing a stromal derived factor 1α plasmid (pSDF1α), a pro-angiogenic gene that is also thought to be involved in the recruitment of mesenchymal stromal cells (MSCs) to sites of injury is described. It is shown that over-expression of SDF1α protein enhanced MSC recruitment and induced vessel-like structure formation by endothelial cells in vitro. When implanted subcutaneously, transcriptomic analysis reveals that endogenous MSCs are recruited and significant angiogenesis is stimulated. Just 1-week after implantation into a calvarial critical-sized bone defect, pSDF1α-activated scaffolds are recruited MSCs and rapidly activate angiogenic and osteogenic programs, upregulating Runx2, Dlx5, and Sp7. At the same time-point, pVEGF-activated scaffolds are recruited a variety of cell types, activating endochondral ossification. The early response induced by both scaffolds leads to complete bridging of the critical-sized bone defects within 4-weeks. The versatile cell-free gene-activated scaffold described in this study is capable of harnessing and enhancing the body's own regenerative capacity and has immense potential in a myriad of applications.

Dual Glyoxalase-1 and ß-Klotho Gene-Activated Scaffold Reduces Methylglyoxal and Reprograms Diabetic Adipose-Derived Stem Cells: Prospects in Improved Wound Healing.

Tissue engineering approaches aim to provide biocompatible scaffold supports that allow healing to progress often in healthy tissue. In diabetic foot ulcers (DFUs), hyperglycemia impedes ulcer regeneration, due to complications involving accumulations of cellular methylglyoxal (MG), a key component of oxidated stress and premature cellular aging which further limits repair. In this study, we aim to reduce MG using a collagen-chondroitin sulfate gene-activated scaffold (GAS) containing the glyoxalase-1 gene (GLO-1) to scavenge MG and anti-fibrotic ß-klotho to restore stem cell activity in diabetic adipose-derived stem cells (dADSCs). dADSCs were cultured on dual GAS constructs for 21 days in high-glucose media in vitro. Our results show that dADSCs cultured on dual GAS significantly reduced MG accumulation (-84%; p < 0.05) compared to the gene-free controls. Similar reductions in profibrotic proteins α-smooth muscle actin (-65%) and fibronectin (-76%; p < 0.05) were identified in dual GAS groups. Similar findings were observed in the expression of pro-scarring structural proteins collagen I (-62%), collagen IV (-70%) and collagen VII (-86%). A non-significant decrease in the expression of basement membrane protein E-cadherin (-59%) was noted; however, the dual GAS showed a significant increase in the expression of laminin (+300%). We conclude that dual GAS-containing Glo-1 and ß-klotho had a synergistic MG detoxification and anti-fibrotic role in dADSC's. This may be beneficial to provide better wound healing in DFUs by controlling the diabetic environment and rejuvenating the diabetic stem cells towards improved wound healing.

Dual delivery gene-activated scaffold directs fibroblast activity and keratinocyte epithelization.

Fibroblasts are the most abundant cell type in dermal skin and keratinocytes are the most abundant cell type in the epidermis; both play a crucial role in wound remodeling and maturation. We aim to assess the functionality of a novel dual gene activated scaffold (GAS) on human adult dermal fibroblasts (hDFs) and see how the secretome produced could affect human dermal microvascular endothelial cells (HDMVECs) and human epidermal keratinocyte (hEKs) growth and epithelization. Our GAS is a collagen chondroitin sulfate scaffold loaded with pro-angiogenic stromal derived factor (SDF-1α) and/or an anti-aging ß-Klotho plasmids. hDFs were grown on GAS for two weeks and compared to gene-free scaffolds. GAS produced a significantly better healing outcome in the fibroblasts than in the gene-free scaffold group. Among the GAS groups, the dual GAS induced the most potent pro-regenerative maturation in fibroblasts with a downregulation in proliferation (twofold, p < 0.05), fibrotic remodeling regulators TGF-ß1 (1.43-fold, p < 0.01) and CTGF (1.4-fold, p < 0.05), fibrotic cellular protein α-SMA (twofold, p < 0.05), and fibronectin matrix deposition (twofold, p < 0.05). The dual GAS secretome also showed enhancements of paracrine keratinocyte pro-epithelializing ability (1.3-fold, p < 0.05); basement membrane regeneration through laminin (6.4-fold, p < 0.005) and collagen IV (8.7-fold, p < 0.005) deposition. Our findings demonstrate enhanced responses in dual GAS containing hDFs by proangiogenic SDF-1α and ß-Klotho anti-fibrotic rejuvenating activities. This was demonstrated by activating hDFs on dual GAS to become anti-fibrotic in nature while eliciting wound repair basement membrane proteins; enhancing a proangiogenic HDMVECs paracrine signaling and greater epithelisation of hEKs.

Anti-Aging ß-Klotho Gene-Activated Scaffold Promotes Rejuvenative Wound Healing Response in Human Adipose-Derived Stem Cells.

Wound healing requires a tight orchestration of complex cellular events. Disruption in the cell-signaling events can severely impair healing. The application of biomaterial scaffolds has shown healing potential; however, the potential is insufficient for optimal wound maturation. This study explored the functional impact of a collagen-chondroitin sulfate scaffold functionalized with nanoparticles carrying an anti-aging gene ß-Klotho on human adipose-derived stem cells (ADSCs) for rejuvenative healing applications. We studied the response in the ADSCs in three phases: (1) transcriptional activities of pluripotency factors (Oct-4, Nanog and Sox-2), proliferation marker (Ki-67), wound healing regulators (TGF-ß3 and TGF-ß1); (2) paracrine bioactivity of the secretome generated by the ADSCs; and (3) regeneration of basement membrane (fibronectin, laminin, and collagen IV proteins) and expression of scar-associated proteins (α-SMA and elastin proteins) towards maturation. Overall, we found that the ß-Klotho gene-activated scaffold offers controlled activation of ADSCs' regenerative abilities. On day 3, the ADSCs on the gene-activated scaffold showed enhanced (2.5-fold) activation of transcription factor Oct-4 that was regulated transiently. This response was accompanied by a 3.6-fold increase in the expression of the anti-fibrotic gene TGF-ß3. Through paracrine signaling, the ADSCs-laden gene-activated scaffold also controlled human endothelial angiogenesis and pro-fibrotic response in dermal fibroblasts. Towards maturation, the ADSCs-laden gene-activated scaffold further showed an enhanced regeneration of the basement membrane through increases in laminin (2.1-fold) and collagen IV (8.8-fold) deposition. The ADSCs also expressed 2-fold lower amounts of the scar-associated α-SMA protein with improved qualitative elastin matrix deposition. Collectively, we determined that the ß-Klotho gene-activated scaffold possesses tremendous potential for wound healing and could advance stem cell-based therapy for rejuvenative healing applications.

SDF-1α gene-activated collagen scaffold enhances provasculogenic response in a coculture of human endothelial cells with human adipose-derived stromal cells.

Novel biomaterials can be used to provide a better environment for cross talk between vessel forming endothelial cells and wound healing instructor stem cells for tissue regeneration. This study seeks to investigate if a collagen scaffold containing a proangiogenic gene encoding for the chemokine stromal-derived factor-1 alpha (SDF-1α GAS) could be used to enhance functional responses in a coculture of human umbilical vein endothelial cells (HUVECs) and human adipose-derived stem/stromal cells (ADSCs). Functional responses were determined by (1) monitoring the amount of junctional adhesion molecule VE-cadherin released during 14 days culture, (2) expression of provasculogenic genes on the 14th day, and (3) the bioactivity of secreted factors on neurogenic human Schwann cells. When we compared our SDF-1α GAS with a gene-free scaffold, the results showed positive proangiogenic determination characterized by a transient yet controlled release of the VE-cadherin. On the 14th day, the coculture on the SDF-1α GAS showed enhanced maturation than its gene-free equivalent through the elevation of provasculogenic genes (SDF-1α-7.4-fold, CXCR4-1.5-fold, eNOS-1.5-fold). Furthermore, we also found that the coculture on SDF-1α GAS secretes bioactive factors that significantly (p < 0.01) enhanced human Schwann cells' clustering to develop toward Bünger band-like structures. Conclusively, this study reports that SDF-1α GAS could be used to produce a bioactive vascularized construct through the enhancement of the cooperative effects between endothelial cells and ADSCs.

SDF-1α Gene-Activated Collagen Scaffold Restores Pro-Angiogenic Wound Healing Features in Human Diabetic Adipose-Derived Stem Cells.

Non-healing diabetic foot ulcers (DFUs) can lead to leg amputation in diabetic patients. Autologous stem cell therapy holds some potential to solve this problem; however, diabetic stem cells are relatively dysfunctional and restrictive in their wound healing abilities. This study sought to explore if a novel collagen-chondroitin sulfate (coll-CS) scaffold, functionalized with polyplex nanoparticles carrying the gene encoding for stromal-derived factor-1 alpha (SDF-1α gene-activated scaffold), can enhance the regenerative functionality of human diabetic adipose-derived stem cells (ADSCs). We assessed the impact of the gene-activated scaffold on diabetic ADSCs by comparing their response against healthy ADSCs cultured on a gene-free scaffold over two weeks. Overall, we found that the gene-activated scaffold could restore the pro-angiogenic regenerative response in the human diabetic ADSCs similar to the healthy ADSCs on the gene-free scaffold. Gene and protein expression analysis revealed that the gene-activated scaffold induced the overexpression of SDF-1α in diabetic ADSCs and engaged the receptor CXCR7, causing downstream ß-arrestin signaling, as effectively as the transfected healthy ADSCs. The transfected diabetic ADSCs also exhibited pro-wound healing features characterized by active matrix remodeling of the provisional fibronectin matrix and basement membrane protein collagen IV. The gene-activated scaffold also induced a controlled pro-healing response in the healthy ADSCs by disabling early developmental factors signaling while promoting the expression of tissue remodeling components. Conclusively, we show that the SDF-1α gene-activated scaffold can overcome the deficiencies associated with diabetic ADSCs, paving the way for autologous stem cell therapies combined with novel biomaterials to treat DFUs.

SDF-1α gene-activated collagen scaffold drives functional differentiation of human Schwann cells for wound healing applications.

Enhancing angiogenesis is the prime target of current biomaterial-based wound healing strategies. However, these approaches largely overlook the angiogenic role of the cells of the nervous system. Therefore, we explored the role of a collagen-chondroitin sulfate scaffold functionalized with a proangiogenic gene stromal-derived factor-1α (SDF-1α)-an SDF-1α gene-activated scaffold on the functional regulation of human Schwann cells (SCs). A preliminary 2D study was conducted by delivering plasmids encoding for the SDF-1α gene into a monolayer of SCs using polyethyleneimine-based nanoparticles. The delivery of the SDF-1α gene into the SCs enhanced the production of proangiogenic vascular endothelial growth factor (VEGF). Subsequently, we investigated the impact of SDF-1α gene-activated scaffold (3D) on the SCs for 2 weeks, using a gene-free scaffold as control. The transfection of the SCs within the gene-activated scaffold resulted in transient overexpression of SDF-1α transcripts and triggered the production of bioactive VEGF that enhanced endothelial angiogenesis. The overexpression of SDF-1α also caused transient activation of the transcription factor c-Jun and supported the differentiation of SCs towards a repair phenotype. This was characterized by elevated expression of neurotrophin receptor p75NGFR. During this developmental stage, the SCs also performed an extensive remodelling of the basement matrix (fibronectin, collagen IV, and laminin) to enrich their environment with the pro-neurogenic matrix protein laminin, revealing an enhanced pro-neurogenic behavior. Together, this study shows that SDF-1α gene-activated scaffold is a highly bioinstructive scaffold capable of enhancing proangiogenic regenerative response in human SCs for improved wound healing.

Characterization of BRCA1 and BRCA2 genetic variants in a cohort of Bahraini breast cancer patients using next-generation sequencing.

BACKGROUND: Breast cancer is the most common malignancy in women worldwide. About 5%-10% are due to hereditary predisposition. The contribution of BRCA1/2 mutations to familial breast cancer in Bahrain has not been explored. The objective of this study was to investigate the spectrum of BRCA1/2 genetic variants and estimate their frequencies in familial breast cancer. We also aim to test the efficiency of the next-generation sequencing (NGS) as a powerful tool for detecting genetic variation within BRCA1/2 genes. METHODS: Twenty-five unrelated female patients diagnosed with familial breast cancer were screened for BRCA1/2 variants. All targeted coding exons and exon-intron boundaries of BRCA1/2 genes were amplified with 167 pairs of primers by NGS. RESULTS: We have identified two deleterious BRCA1/2 variants in two patients, one in BRCA1 gene (c.4850C>A) and other in BRCA2 gene (c.67+2T>C). In addition to the deleterious variants, we identified 24 distinct missense variants of uncertain significance, 10 of them are seen to confer minor but cumulatively significant risk of breast cancer. CONCLUSION: Our data suggest that BRCA1/2 variants may contribute to the pathogenesis of familial breast cancer in Bahrain. It also shows that NGS is useful tool for screening BRCA1/2 genetic variants of probands and unaffected relatives.

Effect of Gum Arabic (Acacia Senegal) supplementation on visceral adiposity index (VAI) and blood pressure in patients with type 2 diabetes mellitus as indicators of cardiovascular disease (CVD): a randomized and placebo-controlled clinical trial.

BACKGROUND: There is a strong association between cardiometabolic risk and adipose tissue dysfunction with great consequences on type 2 diabetic patients. Visceral Adiposity Index (VAI) is an indirect clinical marker of adipose tissue dysfunction. Gum Arabic (GA) is a safe dietary fiber, an exudate of Acacia Senegal. Gum Arabic had shown lipid lowering effect in both humans and animals. The aim of this trial was to determine the effect of GA supplementation on anthropometric obesity marker, Visceral Adiposity Index (VAI) and blood pressure in patients with type 2 diabetes mellitus. METHODS: This randomized, double blinded, placebo controlled trial recruited a total of 91 type 2 diabetic patients (73 females, 18 males), age (mean ± SD) 50.09 ± 9.3 years on hypoglycemic agents and were randomly assigned into two groups, either to consume 30 g of GA or 5 g of placebo daily for 3 months. Anthropometric obesity markers were measured and indices were calculated. Blood pressure was measured and high density lipoprotein (HDL) and triglycerides (TG) were determined in fasting blood samples at the start and end of the study period. RESULTS: After intervention, Gum Arabic decreased BMI and VAI significantly (P < 0.05) in GA group by 2 and 23.7% respectively. Body adiposity index significantly decreased by 3.9% in GA group while there were no significant changes in waist circumference or waist-to-hip ratio (WHR). Systolic blood pressure significantly decreased by 7.6% in GA group and by 2.7% in placebo group from baseline with no significant changes in diastolic blood pressure in the two groups. CONCLUSION: Gum Arabic consumption at a dose of 30 g/d for 3 months may play an effective role in preventing weight gain and modulating adipose tissue dysfunction in type 2 diabetic patients, although no effect has been shown in waist-to-hip ratio. TRIAL REGISTRATION: The trial had been registered as prospective interventional clinical trials in the Pan African Clinical Trial Registry (PACTR) PACTR201403000785219 , on 7th March 2014.

Pro-angiogenic impact of SDF-1α gene-activated collagen-based scaffolds in stem cell driven angiogenesis.

Ensuring an adequate angiogenic response during wound healing is a prevailing clinical challenge in biomaterials science. To address this, we aimed to develop a pro-angiogenic gene-activated scaffold (GAS) that could activate MSCs to produce paracrine factors and influence angiogenesis and wound repair. A non-viral polyethyleneimine (PEI) nanoparticles carrying a gene encoding for stromal derived factor-1 alpha (SDF-1α) was combined with a collagen-chondroitin sulfate scaffold to produce the GAS. The ability of this platform to enhance the angiogenic potential of mesenchymal stem cells (MSCs) was then assessed. We found that the MSCs on GAS exhibited early over-expression of SDF-1α mRNA with the activation of angiogenic markers VEGF and CXCR4. Exposing endothelial cells to conditioned media collected from GAS supported MSCs promoted a 20% increase in viability and 33% increase in tubule formation (p < 0.05). Furthermore, the conditioned media promoted a 50% increase in endothelial cell migration and wound closure (p < 0.005). Gene expression analysis of the endothelial cells revealed that the functional response was associated with up-regulation of angiogenic genes; VEGF, CXCR4, eNOS and SDF-1α. Overall, this study shows collagen-based scaffolds combined with SDF-1α gene therapy can provide enhanced pro-angiogenic response, suggesting a promising approach to overcome poor vasculature during wound healing.

Innovations in gene and growth factor delivery systems for diabetic wound healing.

The rise in lower extremity amputations due to nonhealing of foot ulcers in diabetic patients calls for rapid improvement in effective treatment regimens. Administration of growth factors (GFs) are thought to offer an off-the-shelf treatment; however, the dose- and time-dependent efficacy of the GFs together with the hostile environment of diabetic wound beds impose a major hindrance in the selection of an ideal route for GF delivery. As an alternative, the delivery of therapeutic genes using viral and nonviral vectors, capable of transiently expressing the genes until the recovery of the wounded tissue offers promise. The development of implantable biomaterial dressings capable of modulating the release of either single or combinatorial GFs/genes may offer solutions to this overgrowing problem. This article reviews the state of the art on gene and protein delivery and the strategic optimization of clinically adopted delivery strategies for the healing of diabetic wounds.

Community challenges when using large plastic bottles for Solar Energy Disinfection of Water (SODIS).

BACKGROUND: Communities living in developing countries as well as populations affected by natural or man-made disasters can be left at great risk from water related diseases, especially those spread through the faecal-oral route. Conventional water treatments such as boiling and chlorination can be effective but may prove costly for impoverished communities. Solar water disinfection (SODIS) has been shown to be a cheap and effective way for communities to treat their water. The exposure to sunlight is typically carried out in small volume plastic beverage bottles (up to 2 l). Given the water requirements of consumption and basic personal hygiene, this may not always meet the needs of communities. Recent work has shown 19-L plastic water dispenser containers to be effective SODIS reactors, comparable in efficacy to PET bottles. In this paper we outline the need for studying SODIS in large volumes and discuss 4 main associated challenges. DISCUSSION: Apart from clean water needed for consumption, access to adequate water is essential for sanitation and hygiene. Contamination of treated water through unwashed hands or vessels contributes heavily to the spread of water borne pathogens in communities. Traditional water treatments such as boiling and chlorination can be effective but may prove financially burdensome for low income communities. SODIS in large vessels could be used as a simple method to meet water requirements in low income and disaster affected populations. However, there have been some concerns associated with the conventional SODIS method; we identify the main ones to be: (1) cold or cloudy weather; (2) the fear of leaching in plastic bottles; (3) water turbidity, and; (4) community acceptance. The application of SODIS in large bottles like WDCs has the potential to be an efficient and cost effective method of disinfecting water, either for consumption until more rigorous water treatments can be put in place, or for sanitation and hygiene to curb the spread of fecal contamination. Further research is needed that can address some of the limitations and challenges associated with the use of large bottles for SODIS.

Three hours of perfusion culture prior to 28 days of static culture, enhances osteogenesis by human cells in a collagen GAG scaffold.

In tissue engineering, bioreactors can be used to aid in the in vitro development of new tissue by providing biochemical and physical regulatory signals to cells and encouraging them to undergo differentiation and/or to produce extracellular matrix prior to in vivo implantation. This study examined the effect of short term flow perfusion bioreactor culture, prior to long-term static culture, on human osteoblast cell distribution and osteogenesis within a collagen glycosaminoglycan (CG) scaffold for bone tissue engineering. Human fetal osteoblasts (hFOB 1.19) were seeded onto CG scaffolds and pre-cultured for 6 days. Constructs were then placed into the bioreactor and exposed to 3 × 1 h bouts of steady flow (1 mL/min) separated by 7 h of no flow over a 24-h period. The constructs were then cultured under static osteogenic conditions for up to 28 days. Results show that the bioreactor and static culture control groups displayed similar cell numbers and metabolic activity. Histologically, however, peripheral cell-encapsulation was observed in the static controls, whereas, improved migration and homogenous cell distribution was seen in the bioreactor groups. Gene expression analysis showed that all osteogenic markers investigated displayed greater levels of expression in the bioreactor groups compared to static controls. While static groups showed increased mineral deposition; mechanical testing revealed that there was no difference in the compressive modulus between bioreactor and static groups. In conclusion, a flow perfusion bioreactor improved construct homogeneity by preventing peripheral encapsulation whilst also providing an enhanced osteogenic phenotype over static controls.

Substrate stiffness and contractile behaviour modulate the functional maturation of osteoblasts on a collagen-GAG scaffold.

Anchorage-dependent cells respond to the mechanical and physical properties of biomaterials. One such cue is the mechanical stiffness of a material. We compared the osteogenic potential of collagen-glycosaminoglycan (CG) scaffolds with varying stiffness for up to 6 weeks in culture. The mechanical stiffness of CG scaffolds were varied by cross-linking by physical (dehydrothermal (DHT)) and chemical (1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDAC) and glutaraldehyde (GLUT)) methods. The results showed that all CG substrates allowed cellular attachment, infiltration and osteogenic differentiation. CG scaffolds treated with EDAC and GLUT were mechanically stiffer, retained their original scaffold structure and resisted cellular contraction. Consequently, they facilitated a 2-fold greater cell number, probably due to the pore architecture being maintained, allowing improved diffusion of nutrients. On the other hand, the less stiff substrates cross-linked with DHT allowed increased cell-mediated scaffold contraction, contracting by 70% following 6 weeks (P < 0.01) of culture. This reduction in scaffold area resulted in cells reaching the centre of the scaffold quicker up to 4 weeks; however, at 6 weeks all scaffolds showed similar levels of cellular infiltration, with higher cell numbers found on the stiffer EDAC- and GLUT-treated scaffolds. Analysis of osteogenesis showed that scaffolds cross-linked with DHT expressed higher levels of the late stage bone formation markers osteopontin and osteocalcin (P < 0.01) and increased levels of mineralisation. In conclusion, the more compliant CG scaffolds allowed cell-mediated contraction and supported a greater level of osteogenic maturation of MC3T3 cells, while the stiffer, non-contractible scaffolds resulted in lower levels of cell maturation, but higher cell numbers on the scaffold. Therefore, we found scaffold stiffness had different effects on differentiation and cell number whereby the increased cell-mediated contraction facilitated by the less stiff scaffolds positively modulated osteoblast differentiation while reducing cell numbers.

A novel collagen scaffold supports human osteogenesis--applications for bone tissue engineering.

Collagen glycosaminoglycan (CG) scaffolds have been clinically approved as an application for skin regeneration. The goal of this study has been to examine whether a CG scaffold is a suitable biomaterial for generating human bone tissue. Specifically, we have asked the following questions: (1) can the scaffold support human osteoblast growth and differentiation and (2) how might recombinant human transforming growth factor-beta (TGF-beta(1)) enhance long-term in vitro bone formation? We show human osteoblast attachment, infiltration and uniform distribution throughout the construct, reaching the centre within 14 days of seeding. We have identified the fully differentiated osteoblast phenotype categorised by the temporal expression of alkaline phosphatase, collagen type 1, osteonectin, bone sialo protein, biglycan and osteocalcin. Mineralised bone formation has been identified at 35 days post-seeding by using von Kossa and Alizarin S Red staining. Both gene expression and mineral staining suggest the benefit of introducing an initial high treatment of TGF-beta(1) (10 ng/ml) followed by a low continuous treatment (0.2 ng/ml) to enhance human osteogenesis on the scaffold. Osteogenesis coincides with a reduction in scaffold size and shape (up to 70% that of original). A notable finding is core degradation at the centre of the tissue-engineered construct after 49 days of culture. This is not observed at earlier time points. Therefore, a maximum of 35 days in culture is appropriate for in vitro studies of these scaffolds. We conclude that the CG scaffold shows excellent potential as a biomaterial for human bone tissue engineering.