Combined immunotherapy and antiangiogenic therapy of cancer with microencapsulated cells

Release characteristics of cellulose sulphate capsules and production of cytokines from encapsulated cells

The size and speed of release of proteins of different sizes from standard cellulose sulphate capsules (Cell-in-a-Box®) was investigated. Proteins with molecular weights of up to around 70kD can be released. The conformation, charge and concentration of the protein being released play a role in the release kinetics. Small proteins such as cytokines can be easily released. The ability to produce cytokines at a sustained and predefined level from encapsulated cells genetically engineered to overexpress such cytokines and implanted into patients may aid immunotherapies of cancer as well as infectious and other diseases. It will also allow allogeneic rather than autologous cells to be used. We show that cells encapsulated in polymers of cellulose sulphate are able to release cytokines such as interleukin-2 (IL-2) in a stimulated fashion e.g. using phorbol 12-myristate 13-acetate (PMA) plus ionomycin. Given the excellent documented safety record of cellulose sulphate in patients, these data suggest that clinical usage of the technology may be warranted for cancer treatment and other diseases.

Neem leaf glycoprotein prophylaxis transduces immune dependent stop signal for tumor angiogenic switch within tumor microenvironment

We have reported that prophylactic as well as therapeutic administration of neem leaf glycoprotein (NLGP) induces significant restriction of solid tumor growth in mice. Here, we investigate whether the effect of such pretreatment (25µg/mice; weekly, 4 times) benefits regulation of tumor angiogenesis, an obligate factor for tumor progression. We show that NLGP pretreatment results in vascular normalization in melanoma and carcinoma bearing mice along with downregulation of CD31, VEGF and VEGFR2. NLGP pretreatment facilitates profound infiltration of CD8+ T cells within tumor parenchyma, which subsequently regulates VEGF-VEGFR2 signaling in CD31+ vascular endothelial cells to prevent aberrant neovascularization. Pericyte stabilization, VEGF dependent inhibition of VEC proliferation and subsequent vascular normalization are also experienced. Studies in immune compromised mice confirmed that these vascular and intratumoral changes in angiogenic profile are dependent upon active adoptive immunity particularly those mediated by CD8+ T cells. Accumulated evidences suggest that NLGP regulated immunomodulation is active in tumor growth restriction and normalization of tumor angiogenesis as well, thereby, signifying its clinical translation.

Microencapsulated mammalian cells for simultaneous production of VEGF165b and IFNα

Targeted and simultaneous delivery VEGF165b and IFN alpha in anti-angiogenic and other applications could offer several advantages. For this a system was design using artificial cell alginate-poly-L-lysine- alginate (APA) microcapsules. Result confirms the ability of this system for simultaneous production of these proteins for 28-days. The IFN alpha on a 3 days period increased from 8 ± 0.36 μg/ml at day 10 to 27 ± 2.4 μg/ml at day 16 and then dropped to 6.5 ± 0.5 μg/ml. The VEGF165b on a 3 days period increased from 2.7 ± 0.7 μg/ml at day 10 to 6.9 ± 1 μg/ml at day 16.

Palm tocotrienols decrease levels of pro-angiogenic markers in human umbilical vein endothelial cells (HUVEC) and murine mammary cancer cells

Anti-angiogenic therapy is widely being used to halt tumour angiogenesis. In this study, the anti-angiogenic activity of palm tocotrienol-rich fraction (TRF) and its individual components (γ- and δ-tocotrienol) were first investigated in vitro in human umbilical vein endothelial cells (HUVEC) and 4T1 mouse mammary cancer cells. Results showed reduced levels of Interkeukin (IL)-8 and IL-6, two pro-angiogenic cytokines in HUVEC treated with palm tocotrienols compared with α-tocopherol (α-T) and control cells (P < 0.05). The production of IL-8 and IL-6 was lowest in δ-tocotrienol (δ-T3)-treated cells followed by γ-tocotrienol (γ-T3) and TRF. There was significant (P < 0.05) reduction in IL-8 and vascular endothelial growth factor (VEGF) production in 4T1 cells treated with TRF or δ-T3. There was decreased expression of VEGF and its receptors; VEGF-R1 (fms-like tyrosine kinase, Flt-1) and VEGF-R2 (Kinase-insert-domain-containing receptor, KDR/Flk-2) in tumour tissues excised from mice supplemented with TRF were observed. There was also decreased expression of VEGF-R2 in lung tissues of mice supplemented with TRF. These observations correlate with the smaller tumour size recorded in the tocotrienol-treated mice. This study confirms previous observations that palm tocotrienols exhibit anti-angiogenic properties that may inhibit tumour progression.

Therapeutic cell delivery and fate control in hydrogels and hydrogel hybrids

Hydrogels are synthetic or natural polymer networks that closely mimic native extracellular matrices. As hydrogel-based vehicles are being increasingly employed in therapeutic cell delivery, two inherent traits of most common hydrogels, namely low cell affinity and high cell constraint, have significantly drawn the attention of biomedical community. These two properties lead to the unfavourable settlement of anchorage-dependent cells (ADCs) and unsatisfactory cell delivery or tissue formation in hydrogel matrices. Tissue engineers have correspondingly made many efforts involving chemical modification or physical hybridisation to facilitate ADC settlement and promote tissue formation. On the other hand, these two 'bio-inert' characteristics have particularly favoured oncological cell therapists, who expect to utilize hydrogels to provide sufficiently high confinement of the delivered cells for anti-cancer purposes. In general, control of cell fate and behaviours in these three-dimensional (3D) microenvironments has become the central aim for hydrogel-mediated cell delivery, towards which various models based on hydrogels and their hybrids have emerged. In this paper, we will first review the development of strategies aiming to overcome the aforementioned two 'shortcomings' by (i) establishing ADC survival and (ii) creating space for tissue formation respectively, and then introduce how people take advantage of these 'disadvantages' of hydrogel encapsulation for (iii) an enhanced confinement of cell motion.

Mechanically enhanced microcapsules for cellular gene therapy

Microcapsules bearing a covalently cross-linked coating have been developed for cellular gene therapy as an improvement on alginate-poly(L-lysine)-alginate (APA) microcapsules that only have ionic cross-linking. In this study, two mutually reactive polyelectrolytes, a polycation (designated C70), poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride-co-2-aminoethyl methacrylate hydrochloride) and a polyanion (designated A70), poly(sodium methacrylate-co-2-(methacryloyloxy)ethyl acetoacetate), were used during the microcapsule fabrication. Ca-alginate beads were sequentially laminated with C70, A70, poly(L-lysine) (PLL), and alginate. The A70 reacts with both C70 and PLL to form a approximately 30 microm thick covalently cross-linked interpenetrating polymer network on the surface of the capsules. Confocal images confirmed the location of the C70/A70/PLL network and the stability of the network after 4 weeks implantation in mice. The mechanical and chemical resistance of the capsules was tested with a "stress test" where microcapsules were gently shaken in 0.003% EDTA for 15 min. APA capsules disappeared during this treatment, whereas the modified capsules, even those that had been retrieved from mice after 4-weeks implantation, remained intact. Analysis of solutions passing through model flat membranes showed that the molecular weight cut-off of alginate-C70-A70-PLL-alginate is similar to that of alginate-PLL-alginate. Recombinant cells encapsulated in APA and modified capsules were able to secrete luciferase into culture media. The modified capsules were found to capture some components of regular culture media used during preparation, causing an immune reaction in implanted mice, but use of UltraCulture serum-free medium was found to prevent this immune reaction. In vivo biocompatibility of the new capsules was similar to the APA capsules, with no sign of clinical toxicity on complete blood counts and liver function tests. The increased stability of the covalently modified microcapsules coupled with the acceptable biocompatibility and permeability demonstrated their potential for use as immunoisolation devices in gene therapy.

A generic research paradigm for identification and validation of early molecular diagnostics and new therapeutics in common disorders

Genetically complex disorders continue to confound investigators because of their many underlying factors, both genetic and environmental. In order to tease apart the heritable from the non-heritable contributions to disease, clinicians are relying on researchers in the rapidly expanding fields of high-throughput genomics to identify surrogate clinical endpoints, called biomarkers, that provide a measure of the probability that an individual will succumb to the disease in question. The goals of current biomedical research into complex disorders are to identify and utilize these biomarkers, not only for early detection, but also for personalized treatment with knowledge-guided therapeutics. As the identification of these biomarkers is basically a problem of discovery, we discuss new insights into biomarker detection utilizing the most current genomic technologies available. Additionally, we present here a generic paradigm for the validation of such molecular diagnostics as well as new treatment modalities for complex and increasingly common diseases. Lastly, we delve into the ways genomic biomarkers might be implemented in a clinical setting to allow the subsequent application of targeted therapeutics, which can help the ever expanding groups of individuals experiencing these insidious diseases.

Novel neuroprotective tripeptides and dipeptides

It has long been recognized that thyrotropin-releasing hormone (TRH) and certain TRH analogues are neuroprotective in a variety of animal models of CNS trauma. In addition to these neuroprotective actions, TRH and most TRH analogues have other physiological actions that may not be desirable for treatment of acute injury, such as analeptic, autonomic, and endocrine effects. We have developed a series of dual-substituted TRH analogues that have strong neuroprotective actions, but are largely devoid of these other physiological actions. In addition, we have developed a family of cyclized dipeptides (diketopiperazines), structurally somewhat related to a metabolic product of TRH, that appear even more effective as neuroprotective agents in vitro and in vivo, and may have nootropic properties. Here, we review these novel tripeptide and dipeptide compounds.

Evaluation of human serum albumin as a substitute of foetal bovine serum for cell culture

Cell microencapsulation requires clinically approved materials for their use in pharmaceutical and/or biomedical applications. The overwhelming majority of the literature has used the classical alginate-poly-l-lysine-alginate (APA) capsules for cell immobilization. Although alginate is granted with the medical approval, some of the remaining components such as foetal bovine serum (FBS), an essential ingredient of cell culture media, are not in accordance with the guidelines affirmed by the American Society for Testing and Materials (ASTM) and Food and Drug Administration (FDA). In this paper, human serum albumin (HSA), a medically approved substance, was evaluated as a potential substitute of FBS. The effect of different percentages of FBS and HSA was studied on the proliferation rate, viability and protein production of two different cell lines (C2C12 and baby hamster kidney (BHK) cells), maintained in culture and immobilized in APA microcapsules. Results show that substitution of FBS by HSA reduced the functionality of both non-encapsulated and encapsulated BHK cells. However, immobilized C2C12 cells presented the highest level of viability and a reduction in protein production of 25% when 1% HSA was used. It can be concluded that HSA might be a possible substitute of FBS in order to maintain or transport encapsulated C2C12 cells for short periods of time before implantation.

A multiprong approach to cancer gene therapy by coencapsulated cells

Immune-isolation of nonautologous cells with microencapsulation protects these cells from graft rejection, thus allowing the same recombinant therapeutic cell line to be implanted in different recipients. This approach was successful in treating HER2/neu-expressing tumors in mice by delivering an interleukin-2 fusion protein (sFvIL-2), or angiostatin. However, treatment with interleukin-2 led to profuse inflammation, while angiostatin delivery did not result in long-term tumor suppression, in part due to endothelial cell-independent neovascularization (vascular mimicry). We hypothesize that coencapsulating the two producer cells in the same microcapsules may enhance the efficacy and ameliorate the above side effects. Hence, B16-F0/neu tumor-bearing mice were implanted with sFvIL-2- and angiostatin-secreting cells coencapsulated in the same alginate-poly-L-lysine-alginate microcapsules. However, this protocol only produced an incremental but not synergistic improvement, as measured with greater tumor suppression and improved survival. Compared to the single sFvIL-2 treatment, the coencapsulation protocol showed improved efficacy associated with: mobilization of sFvIL-2 from the spleen; a higher level of cytokine delivery systemically and to the tumors; increased tumor and tumor-associated endothelial cell apoptosis; and a reduced host inflammatory response. However, compared to the single angiostatin treatment, the efficacy was reduced, primarily due to a "bystander" effect in which the angiostatin-secreting cells suffered similar transgene silencing as the coencapsulated cytokine-secreting cells. Nevertheless, the level of "vascular mimicry" of the single angiostatin treatment was significantly reduced. Hence, while there was no synergy in efficacy, an incremental improvement and some reduction in undesirable side effects of inflammation and vascular mimicry were achieved over the single treatments.