Simultaneous Boron Ion-Channel/Growth Factor Receptor Activation for Enhanced Vascularization

The effect of Wharton's jelly-derived stem cells seeded/boron-loaded acellular scaffolds on the healing of full-thickness burn wounds in the rat model

Burn wounds are the most destructive and complicated type of skin or underlying soft tissue injury that are exacerbated by a prolonged inflammatory response. Several cell-based therapeutic systems through the culturing of potent stem cells on modified scaffolds have been developed to direct the burn healing challenges. In this context, a new regenerative platform based on boron (B) enriched-acellular sheep small intestine submucosa (AOSIS) scaffold was designed and used as a carrier for mesenchymal stem cells derived from Wharton's jelly (WJMSCs) aiming to promote the tissue healing in burn-induced rat models. hWJMSCs have been extracted from human extra-embryonic umbilical cord tissue. Thereafter, 96 third-degree burned Wistar male rats were divided into 4 groups. The animals that did not receive any treatment were considered as group A (control). Then, group B was treated just by AOSIS scaffold, group C was received cell-seeded AOSIS scaffold (hWJMSCs-AOSIS), and group D was covered by boron enriched-cell-AOSIS scaffold (B/hWJMSCs-AOSIS). Inflammatory factors, histopathological parameters, and the expression levels of epitheliogenic and angiogenic proteins were assessed on 5, 14 and 21 d post-wounding. Application of the B/hWJMSCs-AOSIS on full-thickness skin-burned wounds significantly reduced the volume of neutrophils and lymphocytes at day 21 post-burning, whilst the number of fibroblasts and blood vessels enhanced at this time. In addition, molecular and histological analysis of wounds over time further verified that the addition of boron promoted wound healing, with decreased inflammatory factors, stimulated vascularization, accelerated re-epithelialization, and enhanced expression levels of epitheliogenic genes. In addition, the boron incorporation amplified wound closure via increasing collagen deposition and fibroblast volume and activity. Therefore, this newly fabricated hWJMSCs/B-loaded scaffold can be used as a promising system to accelerate burn wound reconstruction through inflammatory regulation and angiogenesis stimulation.

PI3K/Akt signaling pathway mediates the effect of low-dose boron on barrier function, proliferation and apoptosis in rat intestinal epithelial cells

Boron is an essential trace element with roles in growth, development, and physiological functions; however, its mechanism of action is still unclear. In this study, the regulatory roles of the PI3K/Akt signaling pathway on boron-induced changes in barrier function, proliferation, and apoptosis in rat intestinal epithelial cells were evaluated. Occludin levels, the proportion of cells in the G2/M phase, cell proliferation rate, and mRNA and protein expression levels of PCNA were higher, while the proportions of cells in the G0/G1 and S phases, apoptosis rate, and caspase-3 mRNA and protein expression levels were lower in cells treated with 0.8 mmol/L boron than in control IEC-6 cells (P < 0.01 or P < 0.05). However, 40 mmol/L boron decreased ZO-1 and Occludin levels, the proportion of cells in the G2/M phase, cell proliferation rate, and mRNA and protein levels of PCNA and increased the apoptosis rate and caspase-3 mRNA expression (P < 0.01 or P < 0.05). After specifically blocking PI3K and Akt signals (using LY294002 and MK-2206 2HCL), 0.8 mmol/L boron had no effects on Occludin, PCNA level, apoptosis rates, and caspase-3 levels (P < 0.05); however, the proliferation rate and PCNA levels decreased significantly (P < 0.01 or P < 0.05). The addition of 40 mmol/L boron did not affect ZO-1 and Occludin levels and did not affect the apoptosis rate or PCNA and caspase-3 levels. These results suggested that the PI3K/Akt signaling pathway mediates the effects of low-dose boron on IEC-6 cells.

Boron-Containing Compounds for Prevention, Diagnosis, and Treatment of Human Metabolic Disorders

The application of natural and synthetic boron-containing compounds (BCC) in biomedical field is expanding. BCC have effects in the metabolism of living organisms. Some boron-enriched supplements are marketed as they exert effects in the bone and skeletal muscle; but also, BCC are being reported as acting on the enzymes and transporters of membrane suggesting they could modify the carbohydrate metabolism linked to some pathologies of high global burden, as an example is diabetes mellitus. Also, some recent findings are showing effects of BCC on lipid metabolism. In this review, information regarding the effects and interaction of these compounds was compiled, as well as the potential application for treating human metabolic disorders is suggested.

Chitosan-Boric Acid Scaffolds for Doxorubicin Delivery in the Osteosarcoma Treatment

Biologically compatible chitosan-based scaffolds have been considered a promising platform for tissue regeneration, tumor treatment, and targeted drug delivery. Chitosan-based scaffolds can be utilized as pH-sensitive drug carriers with targeted drug delivery resulting in less invasive tumor treatments. Further improvement with bioactive ions, such as borate ions, can result in the dual functionality of chitosan carriers provided by simultaneous antitumor efficacy and tissue regeneration. Here, boric acid-containing crosslinked chitosan scaffolds were prepared as delivery systems of doxorubicin, a chemotherapy drug used in the treatment of osteosarcoma. The encapsulation of boric acid was indicated by FTIR spectroscopy, while the ICP-MS analysis indicated the rapid release of boron in phosphate buffer (pH 6.0) and phosphate-buffered saline solution (pH 7.4). The obtained chitosan-boric acid scaffolds exhibit a highly porous and interconnected structure responsible for high swelling capacity, while enzymatic degradation indicated good scaffolds stability during four weeks of incubation at pH 6.0 and 7.4. Furthermore, the release of doxorubicin investigated in phosphate buffers indicated lower doxorubicin concentrations at pH 7.4 with respect to pH 6.0. Finally, the cytotoxicity of prepared doxorubicin-encapsulated scaffolds was evaluated on human sarcoma cells indicating the scaffolds' potential as cytostatic agents.

Versatile-in-All-Trades: Multifunctional Boron-Doped Calcium-Deficient Hydroxyapatite Directs Immunomodulation and Regeneration

Osseointegration of implants depends on several intertwined factors: osteogenesis, angiogenesis, and immunomodulation. Lately, novel reinforcements allowing faster bonding with osseous tissue have been explored intensively. In this study, we hypothesized the use of boron as a major multifunctional ion to confer versatility to calcium-deficient hydroxyapatite (cHA) synthesized by a wet precipitation/microwave reflux method. By synthesis of boron-doped calcium-deficient hydroxyapatite (BcHA), we expected to obtain an osteoimmunomodulatory and regenerative nanoreinforcement. BcHA was found to possess a pure HA phase, a greater surface area (66.41 m²/g, p = 0.028), and cumulative concentrations of Ca (207.87 ± 6.90 mg/mL, p < 0.001) and B (112.70 ± 11.79 mg/mL, p < 0.001) released in comparison to cHA. Osteogenic potential of BcHA was analyzed using human fetal osteoblasts. BcHA resulted in a drastic increase in the ALP activity (1.11 ± 0.11 mmol/gDNA·min, p < 0.001), biomineralization rate, and osteogenic gene expressions compared to cHA. BcHA angiogenic potential was investigated using human umbilical cord vein endothelial cells. Significantly, the highest VEGF-A release (1111.14 ± 87.82 in 4 h, p = 0.009) and angiogenic gene expressions were obtained for BcHA-treated samples. These samples were also observed to induce a more prominent and highly branched tube network. Finally, inflammatory and inflammasome responses toward BcHA were elucidated using human monocyte-derived macrophages differentiated from THP-1s. BcHA exhibited lower CAS-1 release (50.18 ± 5.52 μg/g_DNA μg/gDNA) and higher IL-10 release (126.97 ± 15.05 μg/g_DNA) than cHA. In addition, BcHA treatment led to increased expression of regenerative genes such as VEGF-A, RANKL, and BMP-2. In vitro results demonstrated that BcHA has tremendous osteogenic, angiogenic, and immunomodulatory potential to be employed as a "versatile-in-all-trades" modality in various bone tissue engineering applications.

Interaction between Galectin-3 and Integrins Mediates Cell-Matrix Adhesion in Endothelial Cells and Mesenchymal Stem Cells

Galectin-3 (Gal-3) is a β-galactoside-binding protein that influences various cell functions, including cell adhesion. We focused on the role of Gal-3 as an extracellular ligand mediating cell-matrix adhesion. We used human adipose tissue-derived stem cells and human umbilical vein endothelial cells that are promising for vascular tissue engineering. We found that these cells naturally contained Gal-3 on their surface and inside the cells. Moreover, they were able to associate with exogenous Gal-3 added to the culture medium. This association was reduced with a β-galactoside LacdiNAc (GalNAcβ1,4GlcNAc), a selective ligand of Gal-3, which binds to the carbohydrate recognition domain (CRD) in the Gal-3 molecule. This ligand was also able to detach Gal-3 newly associated with cells but not Gal-3 naturally present on cells. In addition, Gal-3 preadsorbed on plastic surfaces acted as an adhesion ligand for both cell types, and the cell adhesion was resistant to blocking with LacdiNAc. This result suggests that the adhesion was mediated by a binding site different from the CRD. The blocking of integrin adhesion receptors on cells with specific antibodies revealed that the cell adhesion to the preadsorbed Gal-3 was mediated, at least partially, by β1 and αV integrins-namely α5β1, αVβ3, and αVβ1 integrins.

Borax induces osteogenesis by stimulating NaBC1 transporter via activation of BMP pathway

The intrinsic properties of mesenchymal stem cells (MSCs) make them ideal candidates for tissue engineering applications. Efforts have been made to control MSC behavior by using material systems to engineer synthetic extracellular matrices and/or include soluble factors in the media. This work proposes a simple approach based on ion transporter stimulation to determine stem cell fate that avoids the use of growth factors. Addition of borax alone, transported by the NaBC1-transporter, enhanced MSC adhesion and contractility, promoted osteogenesis and inhibited adipogenesis. Stimulated-NaBC1 promoted osteogenesis via the BMP canonical pathway (comprising Smad1/YAP nucleus translocation and osteopontin expression) through a mechanism that involves simultaneous NaBC1/BMPR1A and NaBC1/α₅β₁/α_vβ₃ co-localization. We describe an original function for NaBC1 transporter, besides controlling borate homeostasis, capable of stimulating growth factor receptors and fibronectin-binding integrins. Our results open up new biomaterial engineering approaches for biomedical applications by a cost-effective strategy that avoids the use of soluble growth factors.

Rico et al. propose a simple approach based on borax stimulation of NaBC1 transporter, which enhances FN-binding integrin-dependent mesenchymal stem cell adhesion and contractility, promotes osteogenesis and inhibits adipogenesis. Osteogenic differentiation depends on activation of the BMP pathway through a mechanism that involves simultaneous co-localization of NaBC1 with FN-binding integrins and BMPR1A.

Material-driven fibronectin assembly rescues matrix defects due to mutations in collagen IV in fibroblasts

Basement membranes (BMs) are specialised extracellular matrices that provide structural support to tissues as well as influence cell behaviour and signalling. Mutations in COL4A1/COL4A2, a major BM component, cause a familial form of eye, kidney and cerebrovascular disease, including stroke, while common variants in these genes are a risk factor for intracerebral haemorrhage in the general population. These phenotypes are associated with matrix defects, due to mutant protein incorporation in the BM and/or its absence by endoplasmic reticulum (ER) retention. However, the effects of these mutations on matrix stiffness, the contribution of the matrix to the disease mechanism(s) and its effects on the biology of cells harbouring a collagen IV mutation remain poorly understood. To shed light on this, we employed synthetic polymer biointerfaces, poly(ethyl acrylate) (PEA) and poly(methyl acrylate) (PMA) coated with ECM proteins laminin or fibronectin (FN), to generate controlled microenvironments and investigate their effects on the cellular phenotype of primary fibroblasts harbouring a COL4A2^+/G702D mutation. FN nanonetworks assembled on PEA induced increased deposition and assembly of collagen IV in COL4A2^+/G702D cells, which was associated with reduced ER size and enhanced levels of protein chaperones such as BIP, suggesting increased protein folding capacity of the cell. FN nanonetworks on PEA also partially rescued the reduced stiffness of the deposited matrix and cells, and enhanced cell adhesion through increased actin-myosin contractility, effectively rescuing some of the cellular phenotypes associated with COL4A1/4A2 mutations. The mechanism by which FN nanonetworks enhanced the cell phenotype involved integrin β₁-mediated signalling. Collectively, these results suggest that biomaterials and enhanced integrin signalling via assembled FN are able to shape the matrix and cellular phenotype of the COL4A2^+/G702D mutation in patient-derived cells.