Paclitaxel in tyrosine-derived nanospheres as a potential anti-cancer agent: in vivo evaluation of toxicity and efficacy in comparison with paclitaxel in Cremophor

A review of the mechanisms of anti-cancer activities of some medicinal plants-biochemical perspectives

Cancer is a disease resulting in unbridled growth of cells due to dysregulation in the balance of cell populations. Various management procedures in handling cases of cancer are not without their adverse side effects on the normal cells. Medicinal plants/herbs have been in use in the management of various ailments, including cancer, for a long time. Medicinal plants have been credited with wide safety margins, cost effectiveness, availability and diverse activities. This study reviewed various mechanisms of anti-cancer activities of some medicinal plants from a biochemical perspective. The mechanisms of anti-cancer activities of plant compounds addressed in this article include induction of apoptosis, anti-angiogenic effects, anti-metastasis, inhibition of cell cycle, inhibition of DNA destruction and effects on key enzymes, cytotoxic and anti-oxidant effects. The anti-cancer activities of some of the plants involve more than one mechanism.

Tyrosine-Derived Polymers as Potential Biomaterials: Synthesis Strategies, Properties, and Applications

Peptide-based polymers are evolving as promising materials for various biomedical applications. Among peptide-based polymers, polytyrosine (PTyr)-based and l-tyrosine (Tyr)-derived polymers are unique, due to their excellent biocompatibility, degradability, and functional as well as engineering properties. To date, different polymerization techniques (ring-opening polymerization, enzymatic polymerization, condensation polymerization, solution-interfacial polymerization, and electropolymerization) have been used to synthesize various PTyr-based and Tyr-derived polymers. Even though the synthesis starts from Tyr, different synthesis routes yield different polymers (polypeptides, polyarylates, polyurethanes, polycarbonates, polyiminocarbonate, and polyphosphates) with unique functional characteristics, and these polymers have been successfully used for various biomedical applications in the past decades. This Review comprehensively describes the synthesis approaches, classification, and properties of various PTyr-based and Tyr-derived polymers employed in drug delivery, tissue engineering, and biosensing applications.

Tissue-engineered grafts exploit axon-facilitated axon regeneration and pathway protection to enable recovery after 5-cm nerve defects in pigs

Functional restoration following major peripheral nerve injury (PNI) is challenging, given slow axon growth rates and eventual regenerative pathway degradation in the absence of axons. We are developing tissue-engineered nerve grafts (TENGs) to simultaneously "bridge" missing nerve segments and "babysit" regenerative capacity by providing living axons to guide host axons and maintain the distal pathway. TENGs were biofabricated using porcine neurons and "stretch-grown" axon tracts. TENG neurons survived and elicited axon-facilitated axon regeneration to accelerate regrowth across both short (1 cm) and long (5 cm) segmental nerve defects in pigs. TENG axons also closely interacted with host Schwann cells to maintain proregenerative capacity. TENGs drove regeneration across 5-cm defects in both motor and mixed motor-sensory nerves, resulting in dense axon regeneration and electrophysiological recovery at levels similar to autograft repairs. This approach of accelerating axon regeneration while maintaining the pathway for long-distance regeneration may achieve recovery after currently unrepairable PNIs.

Nanosphere size control by varying the ratio of poly(ester amide) block copolymer blends

HYPOTHESIS

Blending amphiphilic triblock (A-B-A) and diblock (A-B) copolymers comprised of the same hydrophobic tyrosine-derived oligomeric B-block and hydrophilic poly(ethylene glycol) methyl ether (mPEG) A-block can provide highly tunable self-assembled nanosphere particle sizes suitable for biomedical applications.

EXPERIMENT

Triblock and diblock copolymers were synthesized via carbodiimide chemistry and were characterized by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The amount of free PEG present in the purified copolymers was determined using a standard addition calibration curve and GPC peak deconvolution methods. Nanospheres were prepared by co-precipitation of each copolymer and of copolymer blends over a range of mole ratios. Nanospheres were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and % polymer recovery post-preparation.

FINDING

Precise synthesis control produced triblock and diblock copolymers with narrow molecular weight distributions and minimal residual reactants. Self-assembled nanosphere particle sizes were 33 nm for the triblock and 129 nm for the diblock, and the size of their blends increased continuously as a function of mole ratio within that biomedically relevant range. Addition of unreacted PEG had minimal impact on either triblock or diblock nanosphere particle sizes whereas addition of unreacted oligomeric B-block increased nanosphere sizes.

Tyrosol Derived Poly(ester-arylate)s for Sustained Drug Delivery from Microparticles

New biodegradable polymers are needed for use in drug delivery systems to overcome the high burst release, lack of sustained drug release, and acidic degradation products frequently observed in current formulations. Commercially available poly(lactide-co-glycolide) (PLGA) is often used for particle drug release formulations; however, it is often limited by its large burst release and acidic degradation products. Therefore, a biocompatible and biodegradable tyrosol-derived poly(ester-arylate) library has been used to prepare a microparticle drug delivery system which shows sustained delivery of hydrophobic drugs. Studies were performed using polymers with varying hydrophilicity and thermal properties and compared to PLGA. Various drug solubilizing cosolvents were used to load model drugs curcumin, dexamethasone, nicotinamide, and acyclovir. Hydrophobic drugs curcumin and dexamethasone were successfully loaded up to 50 weight percent (wt %), and a linear correlation between drug wt % loaded and the particle glass transition temperature (T_g) was observed. Both curcumin and dexamethasone were visible on the particle surface at 20 wt % loading and higher. By adjusting the polymer concentration during particle formation, release rates were able to be controlled. Release studies of dexamethasone loaded particles with a lower polymer concentration showed a biphasic release profile and complete release after 47 days. Particles prepared using a higher polymer concentration showed sustained release for up to 77 days. Comparably, PLGA showed a traditional triphasic release profile and complete release after 63 days. This novel tyrosol-derived poly(ester-arylate) library can be used to develop injectable, long-term release formulations capable of providing sustained drug delivery.

Opportunities for biomaterials to address the challenges of COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has revealed major shortcomings in our ability to mitigate transmission of infectious viral disease and provide treatment to patients, resulting in a public health crisis. Within months of the first reported case in China, the virus has spread worldwide at an unprecedented rate. COVID-19 illustrates that the biomaterials community was engaged in significant research efforts against bacteria and fungi with relatively little effort devoted to viruses. Accordingly, biomaterials scientists and engineers will have to participate in multidisciplinary antiviral research over the coming years. Although tissue engineering and regenerative medicine have historically dominated the field of biomaterials, current research holds promise for providing transformative solutions to viral outbreaks. To facilitate collaboration, it is imperative to establish a mutual language and adequate understanding between clinicians, industry partners, and research scientists. In this article, clinical perspectives are shared to clearly define emerging healthcare needs that can be met by biomaterials solutions. Strategies and opportunities for novel biomaterials intervention spanning diagnostics, treatment strategies, vaccines, and virus-deactivating surface coatings are discussed. Ultimately this review serves as a call for the biomaterials community to become a leading contributor to the prevention and management of the current and future viral outbreaks.

Local Immunosuppression for Vascularized Composite Allografts: Application of Topical FK506-TyroSpheres in a Nonhuman Primate Model

Transplantation of vascularized composite allografts (VCAs) provides a means of restoring complex anatomical and functional units following burns and other disfigurement otherwise not amenable to conventional autologous reconstructive surgery. While short- to intermediate-term VCA survival is largely dependent on patient compliance with medication, the myriad of side effects resulting from lifelong systemic immunosuppression continue to pose a significant challenge. Topical immunosuppression is therefore a logical and attractive alternative for VCA. Current formulations are limited though, by poor skin penetration but this may be mitigated by conjugation of immunosuppressive drugs to TyroSpheres for enhanced delivery. Therefore, we investigated the topical application of FK506-TyroSpheres (in the form of a gel dressing) in a clinically relevant nonhuman primate VCA model to determine if allograft survival could be prolonged at reduced levels of maintenance systemic immunosuppression. Six Major Histocompatibility Complex (MHC)-mismatched cynomolgus macaques (Macaca fascicularis) served as reciprocal donors and recipients of radial forearm fasciocutaneous flaps. Standard Bacitracin ointment and FK506-TyroSpheres were applied every other day to the VCAs of animals in groups 1 (controls, n = 2) and 2 (experimental, n = 4), respectively, before gradual taper of systemic FK506. Clinical features of VCA rejection still developed when systemic FK506 fell below 10 ng/ml despite application of FK506-TyroSpheres and prolonged VCA survival was not achieved. However, unwanted systemic FK506 absorption was avoided with TyroSphere technology. Further refinement to optimize local drug delivery profiles to achieve and maintain therapeutic delivery of FK506 with TyroSpheres is underway, leveraging significant experience in controlled drug delivery to mitigate acute rejection of VCAs.

Topical Delivery of Immunosuppression to Prolong Xenogeneic and Allogeneic Split-Thickness Skin Graft Survival

Cadaveric skin allograft is the current standard of treatment for temporary coverage of large burn wounds. Porcine xenografts are viable alternatives but undergo α-1,3-galactose (Gal)-mediated hyperacute rejection and are lost by post-operative day (POD) 3 because of naturally occurring antibodies to Gal in primate recipients. Using baboons, we previously demonstrated that xenografts from GalT-KO swine (lacking Gal) provided wound coverage comparable with allografts with systemic immunosuppression. In this study, we investigate topical immunosuppression as an alternative to prolong xenograft survival. Full-thickness wounds in baboons were created and covered with xenogeneic and allogeneic split-thickness skin grafts (STSGs). Animals were treated with slow-release (TyroSphere-encapsulated) topical formulations (cyclosporine-A [CSA] or Tacrolimus) applied 1) directly to the STSGs only, or 2) additionally to the wound bed before STSG and 1). Topical CSA did not improve either xenograft or allograft survival (median: treated grafts = 12.5 days, control = 14 days; P = 0.27) with similar results when topical Tacrolimus was used. Pretreatment of wound beds resulted in a significant reduction of xenograft survival compared with controls (10 vs 14 days; P = 0.0002), with comparable results observed in allografts. This observation was associated with marked reduction of inflammation on histology with Tacrolimus and not CSA. Prolongation of allograft and xenograft survival after application to full-thickness wound beds was not achieved with the current formulation of topical immunosuppressants. Modulation of inflammation within the wound bed was effective with Tacrolimus pretreatment before STSG application and may serve as a treatment strategy in related fields.

Therapeutic efficacy of folate receptor-targeted amphiphilic cyclodextrin nanoparticles as a novel vehicle for paclitaxel delivery in breast cancer

PURPOSE

The aim of this study is to test folate-conjugated cyclodextrin nanoparticles (FCD-1 and FCD-2) as a vehicle for reducing toxicity and increasing the antitumor efficacy of paclitaxel especially for metastatic breast cancer.

METHODS

For the evaluation of PCX-loaded FCD nanoparticles, animal studies were realised in terms of survival rate, tumour size, weight change, metastazis and histopathological examination.

RESULTS

FCD-1 displayed significant advantages such as efficient targeting of folate receptor positive breast cancer cells and having considerably lower toxicity compared to that of Cremophor^®. When loaded with paclitaxel, FCD-1 nanoparticles, which have smaller particle size, neutral zeta potential, high encapsulation efficiency and better loading capacity for controlled release, emerged as an effective formulation in terms of cytotoxicity and high cellular uptake. In an experimental breast cancer model, anticancer activity of these nanoparticles were compatible with that of paclitaxel in Cremophor^® however repeated administrations of FCD-1 nanoparticles were better tolerated by the animals. These nanoparticles were able to localise in tumour site. Both paclitaxel-loaded FCD-1 and FCD-2 significantly reduced tumour burden while FCD-1 significantly improved the survival.

CONCLUSIONS

Folate-conjugated amphiphilic cyclodextrin nanoparticles can be considered as promising Cremophor^®-free, low-toxicity and efficient active drug delivery systems for paclitaxel.

Off-Target Effect of Sildenafil on Postsurgical Erectile Dysfunction: Alternate Pathways and Localized Delivery System

INTRODUCTION

There is no consensus on the best oral phosphodiesterase type 5 inhibitor (PDE5I) for patients undergoing penile rehabilitation after surgical nerve injury.

AIM

To determine the mechanism of PDE5I on cultured neuronal cells and the effectiveness of local drug delivery using nanospheres (NSPs) to sites of nerve injury in a rat model of bilateral cavernous nerve injury (BCNI).

METHODS

The effects of sildenafil, tadalafil, and vardenafil on cyclic adenosine monophosphate, cyclic guanosine monophosphate, and cell survival after exposure to hypoxia and H₂O₂ were measured in PC12, SH-SY5Y, and NTERA-2 (NT2) cell cultures. The effects of phosphodiesterase type 4 inhibitor (PDE4I) and PDE5I on neuronal cell survival were evaluated. Male rats underwent BCNI and were untreated (BCNI), immediately treated with application of empty NSPs (BCNI + NSP), NSPs containing sildenafil (Sild + NSP), or NSPs containing rolipram (Rol + NSP).

MAIN OUTCOME MEASURES

Viability of neuronal cells was measured. Intracavernous pressure changes after cavernous nerve electrostimulation and expression of neurofilament, nitric oxide synthase, and actin in mid-shaft of penis were analyzed 14 days after injury.

RESULTS

Sildenafil and rolipram significantly decreased cell death after exposure to H₂O₂ and hypoxia in PC12, SH-SY5Y, and NT2 cells. PC12 cells did not express PDE5 and knockdown of PDE4 significantly increased cell viability in PC12, SH-SY5Y, and NT2 cells exposed to hypoxia. The ratio of intracavernous pressure to mean arterial pressure and expression of penile neurofilament, nitric oxide synthase, and actin were significantly higher in the Sild + NSP and Rol + NSP groups than in the BCNI and BCNI + NSP groups. Limitations included analysis in only two PDE families using only a single dose.

CONCLUSION

Sildenafil showed the most profound neuroprotective effect compared with tadalafil and vardenafil. Sildenafil- or rolipram-loaded NSP delivery to the site of nerve injury prevented erectile dysfunction and led to increased neurofilament, nitric oxide synthase, smooth muscle content in rat penile tissue after BCNI.

Nanoparticles and nanofibers for topical drug delivery

This review provides the first comprehensive overview of the use of both nanoparticles and nanofibers for topical drug delivery. Researchers have explored the use of nanotechnology, specifically nanoparticles and nanofibers, as drug delivery systems for topical and transdermal applications. This approach employs increased drug concentration in the carrier, in order to increase drug flux into and through the skin. Both nanoparticles and nanofibers can be used to deliver hydrophobic and hydrophilic drugs and are capable of controlled release for a prolonged period of time. The examples presented provide significant evidence that this area of research has - and will continue to have - a profound impact on both clinical outcomes and the development of new products.

Self-Assembly and Critical Aggregation Concentration Measurements of ABA Triblock Copolymers with Varying B Block Types: Model Development, Prediction, and Validation

The dissipative particle dynamics (DPD) simulation technique is a coarse-grained (CG) molecular dynamics-based approach that can effectively capture the hydrodynamics of complex systems while retaining essential information about the structural properties of the molecular species. An advantageous feature of DPD is that it utilizes soft repulsive interactions between the beads, which are CG representation of groups of atoms or molecules. In this study, we used the DPD simulation technique to study the aggregation characteristics of ABA triblock copolymers in aqueous medium. Pluronic polymers (PEG-PPO-PEG) were modeled as two segments of hydrophilic beads and one segment of hydrophobic beads. Tyrosine-derived PEG5K-b-oligo(desaminotyrosyl tyrosine octyl ester-suberate)-b-PEG5K (PEG5K-oligo(DTO-SA)-PEG5K) block copolymers possess alternate rigid and flexible components along the hydrophobic oligo(DTO-SA) chain, and were modeled as two segments of hydrophilic beads and one segment of hydrophobic, alternate soft and hard beads. The formation, structure, and morphology of the initial aggregation of the polymer molecules in aqueous medium were investigated by following the aggregation dynamics. The dimensions of the aggregates predicted by the computational approach were in good agreement with corresponding results from experiments, for the Pluronic and PEG5K-oligo(DTO-SA)-PEG5K block copolymers. In addition, DPD simulations were utilized to determine the critical aggregation concentration (CAC), which was compared with corresponding results from an experimental approach. For Pluronic polymers F68, F88, F108, and F127, the computational results agreed well with experimental measurements of the CAC measurements. For PEG5K-b-oligo(DTO-SA)-b-PEG5K block polymers, the complexity in polymer structure made it difficult to directly determine their CAC values via the CG scheme. Therefore, we determined CAC values of a series of triblock copolymers with 3-8 DTO-SA units using DPD simulations, and used these results to predict the CAC values of triblock copolymers with higher molecular weights by extrapolation. In parallel, a PEG5K-b-oligo(DTO-SA)-b-PEG5K block copolymer was synthesized, and the CAC value was determined experimentally using the pyrene method. The experimental CAC value agreed well with the CAC value predicted by simulation. These results validate our CG models, and demonstrate an avenue to simulate and predict aggregation characteristics of ABA amphiphilic triblock copolymers with complex structures.

Formulation Strategy for the Delivery of Cyclosporine A: Comparison of Two Polymeric Nanospheres

A wide range of nanoparticles has been explored for the delivery of highly hydrophobic drugs, but very few publications provide comparative data of the performance of different nanoparticles. To address this need, this publication compares poly(lactic-co-glycolic acid) (PLGA) nanoparticles and nanospheres made from tyrosine-derived tri-block copolymers (termed TyroSpheres) for their respective performance as carriers for cyclosporine A (CSA). Using previously reported data on PLGA, we followed similar experimental protocols to evaluate the in vitro characteristics of TyroSpheres. Although there are some similarities between the two particle systems for the delivery of CSA, such as effective encapsulation and epidermal skin penetration, several differences were notable. First, the methods of preparation were different, i.e., self-assembly and emulsion-diffusion-evaporation process for TyroSpheres and PLGA, respectively. Second, TyroSpheres provided 7-day diffusion-controlled release, whereas PLGA nanoparticles provided >21-day erosion-controlled release. Third, the size of TyroSpheres was measured to be ~60–70 nm irrespective of drug loading, whereas the size of PLGA nanoparticles (~100–250 nm) was dependent on drug loading and the method of preparation. Overall, this publication provides a direct comparison between two different types of nanoparticles and illuminates the respective advantages and disadvantages, using CSA as a model for the release of highly hydrophobic drugs.

Radiofrequency-triggered tumor-targeting delivery system for theranostics application

In this study, a new type of magnetic tumor-targeting PEGylated gold nanoshell drug delivery system (DOX-TSMLs-AuNSs-PEG) based on doxorubicin-loaded thermosensitive magnetoliposomes was successfully obtained. The reverse-phase evaporation method was used to construct the magnetoliposomes, and then gold nanoshells were coated on the surface of it. The DOX-TSMLs-AuNSs-PEG delivery system was synthesized after SH-PEG2000 modification. This multifunction system was combined with a variety of functions, such as radiofrequency-triggered release, chemo-hyperthermia therapy, and dual-mode magnetic resonance/X-ray imaging. Importantly, the DOX-TSMLs-AuNSs-PEG complex was found to escape from endosomes after cellular uptake by radiofrequency-induced endosome disruption before lysosomal degradation. All results in vitro and in vivo indicated that DOX-TSMLs-AuNSs-PEG is a promising effective drug delivery system for diagnosis and treatment of tumors.

Synthesis and characterization of Fatty acid/amino Acid self-assemblies

In this paper, we discuss the synthesis and self-assembling behavior of new copolymers derived from fatty acid/amino acid components, namely dimers of linoleic acid (DLA) and tyrosine derived diphenols containing alkyl ester pendent chains, designated as "R" (DTR). Specific pendent chains were ethyl (E) and hexyl (H). These poly(aliphatic/aromatic-ester-amide)s were further reacted with poly(ethylene glycol) (PEG) and poly(ethylene glycol methyl ether) of different molecular masses, thus resulting in ABA type (hydrophilic-hydrophobic-hydrophilic) triblock copolymers. We used Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies to evaluate the chemical structure of the final materials. The molecular masses were estimated by gel permeation chromatography (GPC) measurements. The self-organization of these new polymeric systems into micellar/nanospheric structures in aqueous environment was evaluated using ultraviolet/visible (UV-VIS) spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The polymers were found to spontaneously self-assemble into nanoparticles with sizes in the range 196-239 nm and critical micelle concentration (CMC) of 0.125-0.250 mg/mL. The results are quite promising and these materials are capable of self-organizing into well-defined micelles/nanospheres encapsulating bioactive molecules, e.g., vitamins or antibacterial peptides for antibacterial coatings on medical devices.

Y-shaped block copolymer (methoxy-poly(ethylene glycol))2-b-poly(l-glutamic acid): preparation, self-assembly, and use as drug carriers

The nano polymer drugs based on Y-shaped block copolymer mPEG2-PGA show a great potential on the treatment for solid tumors.

Advanced drug delivery nanosystems (aDDnSs): a mini-review

Significant progress has been made in nanoscale drugs and delivery systems employing diverse chemical formulations to facilitate the rate of drug delivery and to improve its pharmacokinetics. Biocompatible nanomaterials have been used as biological markers, contrast agents for imaging, healthcare products, pharmaceuticals, drug-delivery systems as well as in detection, diagnosis and treatment of various types of diseases. The classification of drug delivery nanosystems (DDnSs) is a crucial issue and fundamental efforts on this subject are missing from the literature. This article deals with the classification of DDnSs with a modulatory controlled release profile (MCR) denoted as modulatory controlled release nanosystems (MCRnSs). Conventional (c) and advanced (a) DDnSs are denoted by the acronyms cDDnSs and aDDnSs, and can be composed of a single or more than one biomaterials, respectively. The classification was based on their characteristics such as: surface functionality (f), the nature of biomaterials used and the kind of interactions between biomaterials. The aDDnSs can be classified as hybridic (Hy-) or chimeric (Chi-) based on the nature - same or different respectively - of biomaterials and inorganic materials used. The nature of the elements used for producing advanced biomaterials is of great importance and medicinal chemistry contributes effectively to the production of aDDnSs.

Polymeric nanoparticles-based topical delivery systems for the treatment of dermatological diseases

Human skin not only functions as a permeation barrier (mainly because of the stratum corneum layer) but also provides a unique delivery pathway for therapeutic and other active agents. These compounds penetrate via intercellular, intracellular, and transappendageal routes, resulting in topical delivery (into skin strata) and transdermal delivery (to subcutaneous tissues and into the systemic circulation). Passive and active permeation enhancement methods have been widely applied to increase the cutaneous penetration. The pathology, pathogenesis, and topical treatment approaches of dermatological diseases, such as psoriasis, contact dermatitis, and skin cancer, are then discussed. Recent literature has demonstrated that nanoparticles-based topical delivery systems can be successful in treating these skin conditions. The studies are reviewed starting with the nanoparticles based on natural polymers especially chitosan, followed by those made of synthetic, degradable (aliphatic polyesters), and nondegradable (polyacrylates) polymers; emphasis is given to nanospheres made of polymers derived from naturally occurring metabolites, the tyrosine-derived nanospheres (TyroSpheres™). In summary, the nanoparticles-based topical delivery systems combine the advantages of both the nanosized drug carriers and the topical approach, and are promising for the treatment of skin diseases. For the perspectives, the penetration of ultra-small nanoparticles (size smaller than 40 nm) into skin strata, the targeted delivery of the encapsulated drugs to hair follicle stem cells, and the combination of nanoparticles and microneedle array technologies for special applications such as vaccine delivery are discussed.

Synergistic anti-cancer mechanisms of curcumin and paclitaxel for growth inhibition of human brain tumor stem cells and LN18 and U138MG cells

Glioblastoma, the deadliest brain tumor in humans, responds poorly to conventional chemotherapeutic agents because of existence of highly chemoresistant human brain tumor stem cells (HBTSC). An effective therapeutic strategy is urgently needed to target HBTSC as well as other glioblastoma cells. We explored synergistic efficacy of a low dose of curcumin (CCM) and a low dose of paclitaxel (PTX) in HBTSC and human glioblastoma LN18 (p53 mutant and PTEN proficient) and U138MG (p53 mutant and PTEN mutant) cells. The highest expression of the cancer stem cell markers aldehyde dehydrogenase 1 (ALDH1) and CD133 occurred in HBTSC when compared with LN18 and U138MG cells. Combination of 20μM CCM and 10nM PTX worked synergistically and more effectively than either drug alone in decreasing viability in all cells. Combination of CCM and PTX was highly effective in inducing both morphological and biochemical features of apoptosis. Apoptosis required activation of caspase-8, cleavage of Bid to tBid, increase in Bax:Bcl-2 ratio, and mitochondrial release of cytochrome c, Smac, and apoptosis-inducing factor (AIF). Phosphorylation of Bcl-2 following combination therapy appeared to promote Bax homodimerization and mitochondrial release of pro-apoptotic factors into the cytosol. Increases in activities of cysteine proteases confirmed the completion of apoptotic process. Combination therapy inhibited invasion of cells, reduced expression of survival and proliferation factors and also angiogenic factors, and prevented HBTSC, LN18, and U138MG cells from promoting network formation. Collectively, the combination of CCM and PTX worked as a promising therapy for controlling the growth of HBTSC and other glioblastoma cells.

Development of paclitaxel-TyroSpheres for topical skin treatment

A potential topical psoriasis therapy has been developed consisting of tyrosine-derived nanospheres (TyroSpheres) with encapsulated anti-proliferative paclitaxel. TyroSpheres provide enhancement of paclitaxel solubility (almost 4000 times greater than PBS) by effective encapsulation and enable sustained, dose-controlled release over 72 h under conditions mimicking skin permeation. TyroSpheres offer potential in the treatment of psoriasis, a disease resulting from over-proliferation of keratinocytes in the basal layer of the epidermis, by (a) enabling delivery of paclitaxel into the epidermis at concentrations >100 ng/cm(2) of skin surface area and (b) enhancing the cytotoxicity of loaded paclitaxel to human keratinocytes (IC(50) of paclitaxel-TyroSpheres was approximately 45% lower than that of free paclitaxel). TyroSpheres were incorporated into a gel-like viscous formulation to improve their flow characteristics with no impact on homogeneity, release or skin distribution of the payload. The findings reported here confirm that the TyroSpheres provide a platform for paclitaxel topical administration allowing skin drug localization and minimal systemic escape.