The development of anti-cancer drug delivery systems

Cancer is undoubtedly one of the main threats to global human health and as a result, despite significant advances in the field, new and improved cancer treatments are still in great need. Although chemotherapy (in combination with other therapies) is widely used to suppress the growth of tumours, many of the current anti-cancer drugs suffer from poor selectivity and consequently severe toxicity. In order to conquer these limitations, targeted drug delivery systems have been designed and studied with the primary aim of improving the accuracy of transporting anti-cancer drugs into cancer cells and tissue areas. The overall aim of the work presented in this thesis is to design new anti-cancer drug delivery systems using three different strategies. In Chapter 2, intelligent stimulus-responsive short elastin-like peptides (ELPs) and elastin-based side chain polymers (ESPs) were synthesised. The conformation and aggregation properties of these ELPs and ESPs were studied in different aqueous buffers (varying pH also) using ultraviolet-visible (UV-Vis) spectroscopy and circular dichroism (CD). Of the ELPs investigated, peptide 10 (N-acetylated VPGVG) was found to have the lowest transition temperature at pH 7 (i.e. 45oC). Amongst all the ESPs, PF100-GABA(VPGVG) (29) was proven to have the lowest transition temperature (47oC) which was most likely due to the fact that it had the highest molecular weight. In Chapter 3, gold nanoparticles (GNPs) were synthesised and functionalised with biomolecules including elastin-like peptides (ELPs), elastin-based side chain polymers (ESPs) and the pro-apoptotic peptide D-(KLAKLAK)2 (KLA). The hybrids materials, ELP-GNPs and ESP-GNPs were characterized by UV-Vis, CD and transmission electron microscopy (TEM). The hybrids showed the same temperature sensitive properties as the free ELPs and ESPs previously studied, confirming the successful functionalization of GNPs. The KLA-GNPs were found to have increased anti-cancer activity against HeLa cells compared to the free KLA. In Chapter 4, the pro-apoptotic KLA peptide was conjugated to a series of cell penetrating peptoids (CPPos) to prepare peptoid-peptide hybrids (CPPos-KLA). The anti-cancer, antimicrobial and cell penetrating properties of these peptoid-peptide hybrids were investigated. The results demonstrated an increasing trend in anti-cancer ability of CPPos-KLA hybrids (compared to free KLA) and KLA-CPPo6 (57) gave the lowest IC50 value (ca.8 μM) against HeLa cells

Peptide-functionalized gold nanoparticles : versatile biomaterials for diagnostic and therapeutic applications

Colloidal gold solutions have been used for centuries in a wide variety of applications including staining glass and in the colouring of ceramics. More recently, gold nanoparticles (GNPs) have been studied extensively due to their interesting size-dependent electronic and optical properties. GNPs can be functionalized easily with biomolecules that contain thiols, amines, or even phosphine moieties. For example, the reaction of thiol-containing peptides with GNPs has been used extensively to prepare novel hybrid materials for biomedical applications. A range of different types of peptides can be used to access biomaterials that are designed to perform a specific role such as cancer cell targeting. In addition, specific peptide sequences that are responsive to external stimuli (e.g. temperature or pH) can be used to stabilise/destabilise the aggregation of colloidal GNPs. Such systems have exciting potential applications in the field of colorimetric sensing (including bio-sensing) and in targeted drug delivery platforms. In this review, we will give an overview of the current methods used for preparing peptide functionalized GNPs, and we will discuss their key properties outlining the various applications of this class of biomaterial. In particular, the potential applications of peptide functionalized GNPs in areas of sensing and targeted drug delivery will be discussed

Obstructive sleep apnea affects lacrimal gland function

Purpose: To determine the effect of obstructive sleep apnea syndrome (OSA) on lacrimal gland function and its mechanism. Methods: Male mice aged seven to eight weeks were housed in cages with cyclic intermittent hypoxia to mimic OSA, and the control group was kept in a normal environment. Slit-lamp observation, fluorescein staining, and corneal sensitivity detection are used to assess cornea changes. Tear secretion was detected by phenol red cotton thread, and the pathological changes of lacrimal gland were observed by hematoxylin and eosin staining, oil red O staining, cholesterol and triglyceride kits, immunofluorescence staining, immunohistochemical staining, real-time polymerase chain reaction, transmission electron microscopy, and Western blot. Results: Studies revealed a decreased tear secretion, corneal epithelial defects and corneal hypersensitivity. Myoepithelial cell damage, abnormal lipid accumulation, reduced cell proliferation, increased apoptosis and inflammatory cell infiltration in the lacrimal gland were also seen. Hifα and NF-κB signaling pathways, moreover, were activated, while Pparα was downregulated, in the lacrimal glands of OSA mice. Fenofibrate treatment significantly alleviated pathological changes of the lacrimal gland induced by OSA. Conclusion: OSA disturbs the Hifα/Pparα/NF-κB signaling axis, which affects lacrimal gland structure and function and induces dry eye

Preparation and thermally-induced self-assembly behaviour of elastin-like peptide side-chain polymer-gold nanoparticle (ESP-GNP) hybrids

Thermoresponsive gold nanoparticles were prepared by conjugation of short pentapeptide sequences, containing the elastin-like peptide (ELP) repeat unit Val-Pro-Gly-Val-Gly (VPGVG), to a well-defined active ester prepolymer, poly(pentafluorophenyl acrylate) (pPFPA), itself prepared by RAFT polymerisation. Polymers with number-average chain lengths of 25, 50, 75 and 100 were prepared. The cloud points of their aqueous solutions was found to decrease with chain length and peptide sequence, and varied from 76 to 42 oC. Circular dichroism indicated that the cloud point behaviour was accompanied by a reversible change in peptide conformation from a random coil to a -turn. The resulting thermoresponsive elastin peptide side-chain polymers (ESPs) were then conjugated to gold nanoparticles (GNPs) by ligand exchange. The resulting ESPGNPs similarly displayed thermo-reversible aggregation with transition temperature (Tt) values of 65 and 35 oC for ESPs of chain length 75 and 100, respectively

Cannabinoids Regulate the Diameter of Pericyte-Containing Retinal Capillaries in Rats

Background/Aims: Cannabinoids are vasoactive substances that act as key regulators of arterial tone in the blood vessels supplying peripheral tissues and the central nervous system. We therefore investigated the effect of cannabinoids on retinal capillaries and pericytes. Methods: The effects of cannabinoids on capillary diameters were determined using an ex vivo whole-mount rat retinal model. Western blotting, quantitative PCR, and immunohistochemistry were performed to explore the underlying mechanism. Results: Endogenous cannabinoid 2-arachidonoylglycerol and anandamide and exogenous cannabinoid (R-(+)-WIN55212-2) dilated the noradrenaline-precontracted capillaries in a concentration-dependent manner (1 µM to 0.1 mM). The extent of vasorelaxation was positively correlated with changes in pericyte width. The effects of R-(+)-WIN55212-2 on vasorelaxation and pericyte width were inhibited by a cannabinoid receptor type-1 (CB1) antagonist, AM251 or rimonabant (SR141716A), the nitric oxide synthase inhibitor l-NAME, and the guanylate cyclase inhibitor ODQ. They were also abolished by the removal of the endothelium, but not by the cannabinoid receptor-2 antagonist SR144528, the endothelial cannabinoid receptor antagonist O-1918, or the cyclooxygenase inhibitor indomethacin. Conclusion: The exogenous cannabinoid R-(+)-WIN55212-2 promotes the vasorelaxation of pericyte-containing rat retinal capillaries. This effect of R-(+)-WIN55212-2 is dependent on CB1 and the nitric oxide–cyclic guanosine monophosphate pathway, and requires an intact endothelium

Effect of Microstructure on the Onset Strain and Rate per Strain of Deformation-Induced Martensite Transformation in Q&P Steel by Modeling

The effect of microstructure on the onset strain and rate of deformation-induced martensitic transformation (DIMT) in Q&P steel is studied by a mean-field micromechanics model, in which the residual austenite (RA) and primary martensite (M) phases are treated as elastoplastic particles embedded into the ferrite (F) matrix. The results show that when the volume fraction of the RA increases with a constant fraction of the M, the onset strain of DIMT increases and transformation rate decreases, in contrast to the case of the RA fraction effect with a fixed F fraction. Increasing the volume fraction of the M postpones the DIMT, regardless of the corresponding change from the RA or F fraction, which is similar to the effect of the RA fraction with the constant M but to a higher degree. Conversely, when increasing the fraction of the matrix F, the onset strain of DIMT increases and the rate decreases, and the effect is greater when the corresponding fraction change comes from the M rather than from the RA. Moreover, when the aspect ratio of the RA increases, the onset strain of DIMT decreases with a gradual increase in transformation rate, in agreement with the experimental observation that the equiaxial austenite is more stable in Q&P steels. However, the aspect ratio effect of the M is opposite to that of the RA, indicating that the lath-shaped primary martensite could protect the austenite from DIMT

R-(+)-WIN55212-2 protects pericytes from ischemic damage and restores retinal microcirculatory patency after ischemia/reperfusion injury

Background and purpose: Cannabinoids are vasoactive substances that act as key regulators of arterial tone in the blood vessels supplying peripheral tissues and the central nervous system. This study aimed to investigate the potential of R-(+)-WIN55212-2 (WIN), a cannabinoid receptor 1 agonist (CB1), as a treatment for retinal ischemia/reperfusion (I/R) injury. Experimental approach: Male Wistar rats were subjected to retinal I/R injury by increasing intraocular pressure in the anterior chamber. The rats were randomly divided into four groups: normal control, I/R, vehicle (pre-treated with dimethyl sulfoxide [DMSO] via intraperitoneal injection), and experimental (pre-treated with WIN at a dose of 1 ml/kg via intraperitoneal injection). The rats were sacrificed at different time points of reperfusion (1 hour, 3 hours, 6 hours, and 1 day) after inducing retinal I/R injury, and their retinas were collected for analysis. Oxygen-glucose deprived/reperfusion (OGD/R) was performed by initially perfusing the retinas with oxygenated artificial cerebrospinal fluid (ACSF), then switching to an OGD solution to simulate ischemia, followed by another perfusion with ACSF. Pericyte contraction and the ''no-reflow'' phenomenon were observed using infrared differential interference contrast (IR-DIC) microscopy and immunohistochemistry. Western blot, enzyme-linked immunosorbent assay (ELISA), and nitric oxide (NO) detection were used to explore the potential mechanism. Key results: In both the OGD/R and I/R models, retinal pericytes exhibited persistent contraction even after reperfusion. The ability of WIN to regulate the tone of retinal pericytes and capillaries was specifically blocked by the BKCa inhibitor iberiotoxin (100 nM). WIN demonstrated a protective effect against retinal I/R injury by preserving blood flow in vessels containing pericytes. Pretreatment with WIN alleviated the persistent contraction and apoptosis of retinal pericytes in I/R-induced rats, accompanied by a reduction in intracellular calcium ion (Ca2+) concentration. The expression of CB1 decreased in a time-dependent manner in the I/R group. After I/R injury, endothelium-derived nitric oxide (eNOS) levels were reduced at all time points, which was successfully reversed by WIN therapy except for the 1 day group. Additionally, the downregulation of cyclic guanosine monophosphate (cGMP) and BKCa expression at 3 hours, 6 hours, and 1 day after I/R injury was restored by pretreatment of WIN. Conclusions & implications: WIN exerted its protective effects on retinal I/R injury by inhibiting the contraction and apoptosis of pericytes through the CB1-eNOS-cGMP-BKCa signaling pathway, thus ameliorated the occlusion of retinal capillaries

Enhanced Production of Anti-PD1 Antibody in CHO Cells through Transient Co-Transfection with Anti-Apoptotic Gene Bcl-xL Combined with Rapamycin

CHO cells are often used to produce monoclonal antibodies in mammalian cell expression systems. In the process of large-scale cell culture, apoptosis is related to cell survival and product quality. Over-expressing an anti-apoptotic gene to delay apoptosis and improve cell growth is one of the strategies for improving productivity of monoclonal antibodies. Autophagy inducer rapamycin can extend the culture duration of CHO cells and affect the yield of antibodies. A method was developed for transient co-transfection of anti-apoptotic genes and genes of interest combined with rapamycin to increase the transient expression of the anti-PD1 antibody. Under the optimal transfection conditions, the combination of Bcl-xL and rapamycin can significantly delay cell apoptosis, inhibit cell proliferation, and prolong cell life-time. As a result, anti-PD1 monoclonal antibody expression levels are increased by more than 2 times