Oral infliximab nanomedicines for targeted treatment of inflammatory bowel diseases.

BACKGROUND AND AIMS: Anti-TNF biological therapies such as infliximab (INF) have revolutionised the treatment of inflammatory bowel diseases (IBD). However, serious adverse effects due to systemic administration can significantly impact patient quality of life, limiting their success. Oral nanomedicines propose an innovative solution to provide local delivery to inflamed gastrointestinal tissues, thereby limiting systemic exposure and enhancing therapeutic efficacy. This study aimed to examine the potential of INF nanomedicines for IBD treatment with a focus on nanoparticle (NP) size to modulate the targeting of INF to the epithelial barrier. METHODS: Healthy and inflamed in vitro models of the intestinal epithelial barrier were established to examine the cell interaction of PLGA-PEGNPs of varying particle sizes and polydispersities. INF-loaded NPs were prepared by electrostatic interaction of INF with NPs and examined for their therapeutic efficacy in the inflamed epithelial cell barrier model. RESULTS: NP interaction was significantly enhanced in the inflamed cell barrier model, with increased transport observed for 130 - 300 nm NPs and accumulation of larger NPs (∼600 nm) at the barrier. Delivery of INF directly to the inflamed barrier by ∼600 nm NPs accelerated recovery of barrier integrity and reduced inflammatory cytokine secretion and cytotoxicity in comparison to treatment with INF alone. CONCLUSIONS: Results from this study show that NP particle size can be used to differentially target and treat the inflamed intestinal barrier. Oral INF nanomedicines of modulated size present a novel strategy for the local, targeted treatment of IBD.

Optimising PLGA-PEG Nanoparticle Size and Distribution for Enhanced Drug Targeting to the Inflamed Intestinal Barrier.

Oral nanomedicines are being investigated as an innovative strategy for targeted drug delivery to treat inflammatory bowel diseases. Preclinical studies have shown that nanoparticles (NPs) can preferentially penetrate inflamed intestinal tissues, allowing for targeted drug delivery. NP size is a critical factor affecting their interaction with the inflamed intestinal barrier and this remains poorly defined. In this study we aimed to assess the impact of NP particle size (PS) and polydispersity (PDI) on cell interaction and uptake in an inflamed epithelial cell model. Using 10, 55 and 100 mg/mL poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG), NPs of 131, 312 and 630 nm PS, respectively, were formulated by solvent dispersion. NP recovery was optimised by differential centrifugation to yield NPs of decreased and unimodal size distribution. NP-cell interaction was assessed in healthy and inflamed caco-2 cell monolayers. Results show that NP interaction with caco-2 cells increased with increasing PS and PDI and was significantly enhanced in inflamed cells. Trypan blue quenching revealed that a significant proportion of multimodal NPs were primarily membrane bound, while monomodal NPs were internalized within cells. These results are interesting as the PS and PDI of NPs can be optimised to allow targeting of therapeutic agents to the epithelial membrane and/or intracellular targets in the inflamed intestinal epithelium.

The future of nanomedicine in optimising the treatment of inflammatory bowel disease.

There have been major advancements in the treatment of inflammatory bowel disease (IBD) over the past three decades. However despite significant progress, the best available treatments continue to demonstrate variable efficacy in patients and are associated with adverse effects. Therefore there remains an unmet clinical need for ongoing therapeutic advances for IBD. In recent years nanomedicines have emerged as promising diagnostic and therapeutic tools. Nanoparticles in particular show promise to facilitate targeted oral drug delivery in IBD. Here we discuss the pitfalls of current therapies and explore the potential for nanoparticles to improve the treatment of IBD. This review examines the range of conventional and novel therapies which have benefited from nanoparticle-mediated delivery and highlights the proven therapeutic efficacy of this approach in preclinical models. These strategies under development represent a novel and innovative treatment for IBD.

A 1-year prospective study of the effect of infliximab on bone metabolism in inflammatory bowel disease patients.

OBJECTIVES: Infliximab (IFX) treatment has shown potentially beneficial effects on bone metabolism in inflammatory bowel disease (IBD) patients. We aimed to prospectively evaluate the impact of IFX treatment on bone metabolism in antitumour necrosis factor (TNF)-α-naive IBD patients using established bone metabolism markers and an in-vitro osteoblast model. MATERIALS AND METHODS: A total of 37 anti-TNFα-naive IBD patients and 20 healthy controls were included. All measurements were performed at baseline and repeated in IBD patients following IFX therapy. Bone mineral density was measured by dual-energy X-ray absorptiometry. Parathyroid hormone, vitamin D, osteoprotegerin, soluble receptor activator of nuclear factor B ligand and proinflammatory and anti-inflammatory cytokines were measured. Bone formation was measured using osteocalcin (OC) and procollagen type 1N propeptide, and bone resorption was measured using serum type 1 collage c-telopeptide. The effect of control and IBD patient sera on human osteoblast viability and differentiation was analysed. RESULTS: OC level was higher in controls than IBD patients (P=0.018). After IFX, OC and procollagen type 1N propeptide increased significantly (P=0.002 and 0.011) and (P<0.001 and P=0.016) at weeks 6 and 30 after treatment, respectively. There was a nonsignificant decrease in serum type 1 collage c-telopeptide. After IFX therapy, proinflammatory cytokines TNF-α, interleukin-6 and interleukin-13 decreased significantly (P=0.016, week 54; P=0.005, week 6 and P=0.025, week 6), respectively. Sera from IBD patients before IFX showed increased osteoblast viability compared with the controls (P=0.003 to P<0.005), but induced reduced osteoblast differentiation. After IFX, viability reduced to control levels, but osteoblast differentiation increased (P=0.041). CONCLUSION: IFX treatment induced beneficial effects on bone metabolism. Osteoblast culture results suggest that IBD patients may have increased osteoblast viability, but reduced differentiation, which has implications for bone strength.

Adalimumab Therapy Has a Beneficial Effect on Bone Metabolism in Patients with Crohn's Disease.

BACKGROUND: Infliximab has been shown to have beneficial effects on bone metabolism in patients with Crohn's disease (CD) although as yet the exact mechanisms have not been fully elucidated. AIM: To evaluate the impact of adalimumab therapy on bone metabolism using a combined in vivo and in vitro model. METHODS: Parathyroid hormone, vitamin D, bone formation markers, bone resorption marker, pro-inflammatory cytokines, anti-inflammatory cytokines, osteoprotegerin, and sRANKL were measured in control patients and pre- and post-treatment with adalimumab in CD patients. The effect of control patients' and pre- and post-treatment CD patients' sera on human osteoblasts (hFOB 1.19) in vitro cell viability and differentiation was also analyzed. RESULTS: There was a significant increase in bone formation markers osteocalcin (P < 0.05) and procollagen type 1 N-terminal propeptide (P < 0.01) at 1 and 3 months post-treatment. Moreover, there was a sustained but not significant fall in serum CTx, a bone resorption marker. No significant change was seen over time with other parameters measured. Serum from CD patients pre-treated with adalimumab showed increased osteoblast viability compared with that of post-treated patients at 6 months (P = 0.002) and controls. However, post-adalimumab treatment sera at 6 months appeared to increase osteoblast differentiation (P = 0.001), which is likely to be important in new bone formation. CONCLUSIONS: This first study evaluating the role of adalimumab as a possible bone protector in Crohn's disease patients has shown that similar to infliximab, adalimumab has complex and potentially beneficial effects on bone metabolism.

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.