Design and Characterization of an Osmotic Pump System for Optimal Feeding and pH Control in E. coli Culture to Increase Biomass.

Background: Batch cultures used for various purposes, such as expression screening and recombinant protein production in laboratories, usually have some drawbacks due to the bolus addition of carbon sources, such as glucose and buffers, that lead to overflow metabolism, decreased pH, high osmolality, low biomass yield, and low protein production. Objectives: This study aimed to overcome the problems of batch culture using the controlled release concept by a controlled porosity osmotic pump (CPOP) system. Methods: The CPOP was formulated with glucose as a carbon source feeding and sodium carbonate as a pH modifier in the core of the tablet that was coated with a semipermeable membrane containing cellulose acetate and polyethylene glycol (PEG) 400. The release rate was regulated with Eudragit L100 as a retardant agent in the core and PEG 400 as a pore-former agent in the coating membrane. Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to elucidate compatibility between components and release mechanism, respectively. The in-vitro release of glucose and Na2CO3 studies were performed for 24 hours in a mineral culture medium (M9). Then, the effectiveness of CPOP in the growth of Escherichia coli (E. coli BL21) as a microorganism model was evaluated. Glucose consumption, changes in medium's pH, and acetate concentration as a by-product were also monitored during the bacterial growth. Results: Fourier-transform infrared spectroscopy confirmed the compatibility between the components in the osmotic pump, and SEM elucidated the release mechanism due to in-situ delivery pores created by dissolving soluble components (PEG 400) on the coated membrane upon contact with the dissolution medium. The in-vitro release studies indicated that the osmotic pump was able to deliver glucose and sodium carbonate in a zero-order manner. The use of CPOP in E. coli (BL21) cultivation resulted in a statistically significant improvement in biomass (over 80%), maintaining the pH of the medium (above 6.8) during the exponential phase, and reducing metabolic by-product formation (acetate), compared to bolus feeding (P < 0.05). Conclusions: The use of CPOP, which is capable of controlled release of glucose as a carbon source and sodium carbonate as a pH modifier, can overcome the drawbacks of bolus feeding, such as decreased pH, increased acetate concentration, and low productivity. It has a good potential for commercialization.

Comparing the Soluble Form of Recombinant Human Insulin-like Growth Factor-1 (rhIGF-1) in Escherichia coli Using Thioredoxin as Fused and Co-expressed Protein.

INTRODUCTION: Insulin-like growth factor-1 (IGF-1) is a single-chain polypeptide with various physiological functions. Escherichia coli is one of the most desirable hosts for recombinant protein production, especially for human proteins whose post-translation modifications are not essential for their bioactivity, such as hIGF-1. OBJECTIVES: In this study, bacterial thioredoxin (Trx) was studied as a fused and non-fused protein to convert the insoluble form of recombinant human IGF-1 (rhIGF-1) to its soluble form in E. coli. METHODS: The rhIGF-1 was expressed in the E. coli Origami strain in the form of fused-Trx. It was co-expressed with Trx and then purified and quantified. In the next step, the biological activity of rhIGF-1 was evaluated by alkaline phosphatase (ALP) activity assay in human adipose-derived stem cells (hASCs) regarding the differentiation enhancement effect of IGF-1 through the osteogenic process. RESULTS: Results showed that Trx in both the fused and non-fused forms had a positive effect on the production of the soluble form of rhIGF-1. A significant increase in ALP activity in hASCs after rhIGF-1 treatment was observed, confirming protein bioactivity. CONCLUSION: It was strongly suggested that the overproduction of Trx could increase the solubility of co-expressed recombinant proteins by changing the redox state in E. coli cells.

Mesenchymal stem cell therapy using Pal-KTTKS-enriched carboxylated cellulose improves burn wound in rat model.

Despite the great progress in developing wound dressings, delayed wound closure still remains a global challenge. Thus, developing novel wound dressings and employing advanced strategies, including tissue engineering, are urgently desired. The carboxylated cellulose was developed through the in situ synthesis method and further reinforced by incorporating pal-KTTKS to stimulate collagen synthesis and improve wound healing. The developed composites supported cell adhesion and proliferation and showed good biocompatibility. To boost wound-healing performance, adipose-derived mesenchymal stem cells (MSC) were seeded on the pal-KTTKS-enriched composites to be implanted in a rat model of burn wound healing. Healthy male rats were randomly divided into four groups and wound-healing performance of Vaseline gauze (control), carboxylated cellulose (CBC), pal-KTTKS-enriched CBC (KTTKS-CBC), and MSCs seeded on the KTTKS-CBC composites (MSC-KTTKS-CBC) were evaluated on days 3, 7, and 14 post-implantation. In each group, the designed therapeutic dressings were renewed every 5 days to increase wound-healing performance. We found that KTTKS-CBC and MSC-KTTKS-CBC composites exhibited significantly better wound healing capability, as evidenced by significantly alleviated inflammation, increased collagen deposition, improved angiogenesis, and considerably accelerated wound closure. Nevertheless, the best wound-healing performance was observed in the MSC-KTTKS-CBC groups among all four groups. This research suggests that the MSC-KTTKS-CBC composite offers a great deal of promise as a wound dressing to enhance wound regeneration and expedite wound closure in the clinic.

7SK small nuclear RNA (Rn7SK) induces apoptosis through intrinsic and extrinsic pathways in human embryonic kidney cell line.

BACKGROUND: Rn7SK, a highly conserved small nuclear non-coding RNA, controls Polymerase II transcription machinery by activating of the Positive Transcriptional Elongation Factor b (P-TEFb). Apart from its role in transcriptional regulation, the potential functions of Rn7SK in cell apoptosis are poorly understood. In a previous study, we demonstrated that overexpression of 7SK induces apoptosis in HEK cells. However, it remains unclear whether 7SK-mediated apoptosis induction is exerted through the intrinsic or extrinsic pathways. METHODS AND RESULTS: Rn7SK was overexpressed in HEK 293T cell line using Lipofectamine 2000 reagent to investigate its potential apoptotic functions. The overexpression of Rn7SK resulted in reduced cell viability through the induction of apoptosis, as evidenced by MTT assay and Annexin V/PI staining. Concurrently, alterations in the expression levels of key apoptosis-related genes were observed, as determined by quantitative RT-PCR. Furthermore, Rn7SK overexpression led to a decrease in cell proliferation, as assessed by colony formation assay and growth curve analysis. This reduction was associated with downregulated expression of key proliferative-related genes. Additionally, the migration and invasion capabilities of cells were significantly inhibited upon upregulation of Rn7SK, as demonstrated by transwell assays. CONCLUSIONS: This study suggests the apoptotic role of 7SK through both intrinsic and extrinsic pathways, necessitating further investigation into its underlying mechanisms.

Overexpression of SIRT6 alleviates apoptosis and enhances cell viability and monoclonal antibody expression in CHO-K1 cells.

BACKGROUND: Chinese hamster ovary (CHO) cells are the most predominantly utilized host for the production of monoclonal antibodies (mAbs) and other complex glycoproteins. A major challenge in the process of CHO cell culture is the occurrence of cell death following different stressful conditions, which hinders the production yield. Engineering genes involved in pathways related to cell death is a remarkable strategy to delay apoptosis, improve cell viability and enhance productivity. SIRT6 is a stress-responsive protein that regulates DNA repair, maintains genome integrity, and is critical for longevity and cell survival in organisms. METHODS AND RESULTS: In this study, SIRT6 was stably overexpressed in CHO-K1 cells and the impact of its expression on apoptosis related gene expression profile, viability, apoptosis, and mAb productivity was investigated. While a significant increase was observed in Bcl-2 mRNA level, caspase-3 and Bax mRNA levels were decreased in the SIRT6 engineered cells compared to the parental CHO-K1 cells. Moreover, improved cell viability and decreased rate of apoptotic progression was observed in a SIRT6-derived clone in comparision to the CHO-K1 cells during 5 days of batch culture. anti-CD52 IgG1 mAb titers were improved up to 1.7- and 2.8-fold in SIRT6-derived clone during transient and stable expression, respectively. CONCLUSIONS: This study indicates the positive effects of SIRT6 overexpression on cell viability and anti-CD52 IgG1 mAb expression in CHO-K1 cells. Further studies are needed to examine the potential of SIRT6-engineered host cells for the production of recombinant biotherapeutics in industrial settings.

Repairing rat calvarial defects by adipose mesenchymal stem cells and novel freeze-dried three-dimensional nanofibrous scaffolds.

Introduction: Treatment of critical-sized bone defects is challenging. Tissue engineering as a state-of-the-art method has been concerned with treating these non-self-healing bone defects. Here, we studied the potentials of new three-dimensional nanofibrous scaffolds (3DNS) with and without human adipose mesenchymal stem cells (ADSCs) for reconstructing rat critical-sized calvarial defects (CSCD). Methods: Scaffolds were made from 1- polytetrafluoroethylene (PTFE), and polyvinyl alcohol (PVA) (PTFE/ PVA group), and 2- PTFE, PVA, and graphene oxide (GO) nanoparticle (PTFE/ PVA/GO group) and seeded by ADSCs and incubated in osteogenic media (OM). The expression of key osteogenic proteins including Runt-related transcription factor 2 (Runx2), collagen type Iα (COL Iα), osteocalcin (OCN), and osteonectin (ON) at days 14 and 21 of culture were evaluated by western blot and immunocytochemistry methods. Next, 40 selected rats were assigned to five groups (n=8) to create CSCD which will be filled by scaffolds or cell-containing scaffolds. The groups were denominated as the following order: Control (empty defects), PTFE/PVA (PTFE/PVA scaffolds implant), PTFE/PVA/GO (PTFE/PVA/GO scaffolds implant), PTFE/PVA/Cell group (PTFE/PVA scaffolds containing ADSCs implant), and PTFE/PVA/GO/Cell group (PTFE/PVA/GO scaffolds containing ADSCs implant). Six and 12 weeks after implantation, the animals were sacrificed and bone regeneration was evaluated using computerized tomography (CT), and hematoxylin-eosin (H&E) staining. Results: Based on the in-vitro study, expression of bone-related proteins in ADSCs seeded on PTFE/PVA/GO scaffolds were significantly higher than PTFE/PVA scaffolds and TCPS (P<0.05). Based on the in-vivo study, bone regeneration in CSCD were filled with PTFE/PVA/GO scaffolds containing ADSCs were significantly higher than PTFE/PVA scaffolds containing ADSCs (P<0.05). CSCD filled with cell-seeded scaffolds showed higher bone regeneration in comparison with CSCD filled with scaffolds only (P<0.05). Conclusion: The data provided evidence showing new freeze-dried nanofibrous scaffolds formed from hydrophobic (PTFE) and hydrophilic (PVA) polymers with and without GO provide a suitable environment for ADSCs due to the expression of bone-related proteins. ADSCs and GO in the implanted scaffolds had a distinct effect on the bone regeneration process in this in-vivo study.

Therapeutic and Protective Potential of Mesenchymal Stem Cells, Pharmaceutical Agents and Current Vaccines Against COVID-19.

It has been almost 18 months since the first outbreak of COVID-19 disease was reported in Wuhan, China. This unexpected devastating phenomenon, raised a great deal of concerns and anxiety among people around the world and imposed a huge economic burden on the nations' health care systems. Accordingly, clinical scientists, pharmacologists and physicians worldwide felt an urgent demand for a safe, effective therapeutic agent, treatment strategy or vaccine in order to prevent or cure the recently-emerged disease. Initially, due to the lack of specific pharmacological agents and approved vaccines to combat the COVID-19, the disease control in the confirmed cases was limited to supportive care. Accordingly, repositioning or repurposing current drugs and examining their possible therapeutic efficacy received a great deal of attention. Despite revealing promising results in some clinical trials, the overall results are conflicting. For this reason, there is an urgent need to seek and investigate other potential therapeutics. Mesenchymal stem cells (MSC), representing immunomodulatory and regenerative capacity to treat both curable and intractable diseases, have been investigated in COVID-19 clinical trials carried out in different parts of the world. Nevertheless, up to now, none of the MSC-based approaches has been approved in controlling COVID-19 infection. Thanks to the fact that the final solution for defeating the pandemic is developing a safe, effective vaccine, enormous efforts and clinical research have been carried out. In this review, we will concisely discuss the safety and efficacy of the most relevant pharmacological agents, MSC-based approaches and candidate vaccines for treating and preventing COVID-19 infection.

Acetate Kinase a Antisense Delivery by PAMAM Dendrimer for Decreasing Acetate Production and Increasing the Production of Recombinant Albumin in E. coli.

BACKGROUND: Acetate accumulation in the culture medium is known as an inhibitor in recombinant protein production in Escherichia coli. Various approaches have been proposed and evaluated to overcome this challenge and reduce the concentration of acetate. In this study, we examined the effect of acetate kinase A antisense on acetate production rate in E. coli We also used PAMAM dendrimers as a suitable delivery agent for antisense transformation into E. coli host cell. OBJECTIVE: This study aimed to decrease acetate production as a by-product using an antisense-dendrimer complex to increase mass cell and subsequently recombinant Albumin production in E. coli. MATERIALS AND METHODS: Here, to study the effect of this treatment on recombinant protein production, we used pET22b/HAS construct. The ackA gene expression was inhibited by designed antisense to reduce acetate concentration in culture medium. AckA antisense was transferred to E. coli by PAMAM dendrimer. Finally, ackA expression and recombinant Albumin production were evaluated Real-Time PCR and densitometry, respectively. RESULTS: Our data showed, designed antisense lead to reduction of acetate kinase gene expression and subsequently acetate concentration in the culture medium. Finally, acetate concentration reduction and cell mass increase result in enhanced recombinant Alb production in the treated group (1.25 mg.mL-1) compare to the control group ( 0.59 mg.mL-1). CONCLUSIONS: Reduction of acetate in E. coli fermentation process decreased the recombinant Alb production following cell growth and cell mass increase. In the current study, we showed that an antisense can be a useful tool for ackA gene expression reduction. Also, we noted that PAMAM dendrimer could be a proper delivery agent for oligonucleotide antisense transformation into bacterial cells.

Applications of Bacterial Cellulose as a Natural Polymer in Tissue Engineering.

Choosing the material with the best regeneration potential and properties closest to that of the extracellular matrix is one of the main challenges in tissue engineering and regenerative medicine. Natural polymers, such as collagen, elastin, and cellulose, are widely used for this purpose in tissue engineering. Cellulose derived from bacteria has excellent mechanical properties, high hydrophilicity, crystallinity, and a high degree of polymerization and, therefore, can be used as scaffold/membrane for tissue engineering. In the current study, we reviewed the latest trends in the application of bacterial cellulose (BC) polymers as a scaffold in different types of tissue, including bone, vascular, skin, and cartilage. Also, we mentioned the biological and mechanical advantages and disadvantages of BC polymers. Given the data presented in this study, BC polymer could be suggested as a favorable natural polymer in the design of tissue scaffolds. Implementing novel composites that combine this polymer with other materials through modern or rapid prototyping methods can open up a great prospect in the future of tissue engineering and regenerative medicine.

Monocyclic Peptides: Types, Synthesis and Applications.

Peptides are considered to be appropriate tools in various biological fields. They can be primarily used for the rational design of bioactive molecules. They can act as ligands in the development of targeted therapeutics as well as diagnostics, can be used in the design of vaccines or can be employed in agriculture. Peptides can be classified in two broad structural classes: linear and cyclic peptides. Monocyclic peptides are a class of polypeptides with one macrocyclic ring that bears advantages, such as more selective binding and uptake by the target receptor, as well as higher potency and stability compared to linear types. This paper provides an overview of the categories, synthesis methods and various applications of cyclic peptides. The various applications of cyclic peptides include their use as pro-apoptotic and anti-microbial agents, their application as targeting ligands in drug delivery and diagnostic agents, as well as agricultural and therapeutics applications that are elaborated and discussed in this paper.

Optimization of Topography and Surface Properties of Polyacrylonitrile-Based Electrospun Scaffolds via Nonoclay Concentrations and its Effect on Osteogenic Differentiation of Human Mesenchymal Stem Cells.

Nowadays, mesenchymal stem cells (MSCs) are the most widely used cell sources for bone regenerative medicine. Electrospun polyacrylonitrile (PAN)-based scaffolds play an important role in bone tissue engineering due to their good mechanical properties, which could be enhanced by the presence of nanoparticles such as nanoclay. This study evaluated the in-vitro effect of different concentrations of nanoclay in surface characteristic properties of PAN-based electrospun nanofiber scaffolds and the osteogenic differentiation ability of adipose-derived mesenchymal stem cells (AD-MSCs). After electrospinning nanofibers, their structure were assessed through some characterization tests. Then AD-MSCs isolation and characterization were done, and the cell attachment and the biocompatibility were determined. Finally, osteogenic differentiation-related markers, genes, and proteins were studied. Clay-PAN25% electrospun nanofiber scaffold could support attachment, proliferation, and osteogenic differentiation of AD-MSCs better than other groups. Also, nanoclay could enhance the properties of PAN-based scaffolds, such as fiber diameter, topography, surface charge, hydrophilicity, roughness, and degradation, as well as osteogenic differentiation of cells. As a result, Clay-PAN25% with the highest concentration of nanoclay was found as a promising biodegradable and cost-effective scaffold for osteogenic differentiation of AD-MSCs.

Regenerative Medicine Under the Control of 3D Scaffolds: Current State and Progress of Tissue Scaffolds.

Currently, combining stem cells (SCs) with biomaterial scaffolds provides a promising strategy for the future of biomedicine and regenerative medicine (RG). The cells need similar substrates of the extracellular matrix (ECM) for normal tissue development, which signifies the importance of three dimensional (3D) scaffolds to determine cell fate. Herein, the importance and positive contributions of corresponding 3D scaffolds on cell functions, including cell interactions, cell migrations, and nutrient delivery, are presented. Furthermore, the synthesis techniques which are recruited to fabricate the 3D scaffolds are discussed, and the related studies of 3D scaffold for different tissues are also reported in this paper. This review focuses on 3D scaffolds that have been used for tissue engineering purposes and directing stem cell fate as a means of producing replacements for biomedical applications.

Freeze-dried multiscale porous nanofibrous three dimensional scaffolds for bone regenerations.

Introduction: Simulating hydrophobic-hydrophilic composite face with hierarchical porous and fibrous architectures of bone extracellular matrix (ECM) is a key aspect in bone tissue engineering. This study focused on the fabrication of new three-dimensional (3D) scaffolds containing polytetrafluoroethylene (PTFE), and polyvinyl alcohol (PVA), with and without graphene oxide (GO) nanoparticles using the chemical cross-linking and freeze-drying methods for bone tissue application. The effects of GO on physicochemical features and osteoinduction properties of the scaffolds were evaluated through an in vitro study. Methods: After synthesizing the GO nanoparticles, two types of 3D scaffolds, PTFE/PVA (PP) and PTFE/PVA/GO (PPG), were developed by cross-linking and freeze-drying methods. The physicochemical features of scaffolds were assessed and the interaction of the 3D scaffold types with human adipose mesenchymal stem cells (hADSCs) including attachment, proliferation, and differentiation to osteogenic like cells were investigated. Results: GO nanoparticles were successfully synthesized with no agglomeration. The blending of PTFE as a hydrophobic polymer with PVA polymer and GO nanoparticles (hydrophilic compartments) were successful. Two types of 3D scaffolds had nano topographical structures, good porosities, hydrophilic surfaces, thermal stabilities, good stiffness, as well as supporting the cell attachments, proliferation, and osteogenic differentiation. Notably, GO incorporating scaffolds provided a better milieu for cell behaviors. Conclusion: Novel multiscale porous nanofibrous 3D scaffolds made from PTFE/ PVA polymers with and without GO nanoparticles could be an ideal candidate for bone tissue engineering as a 3D template.

Peptide dendrimers as valuable biomaterials in medical sciences.

Peptides are oligomers of amino acids, which have been used in a wide range of applications, particularly in medical and pharmaceutical sciences. Linear peptides have been extensively developed in various fields of medicine as therapeutics or targeting agents. The branched structure of peptide dendrimers with peptide (commonly, poly l­Lysine) or non-peptide (commonly poly­amidoamine) core, often exhibits valuable novel features, improves stability and enhances the functionality of peptide in comparison with small linear peptides. The potential applications of Branched and hyper-branched peptidic structures which are known as peptide dendrimers in biomedical sciences have been approved vastly. A peptide dendrimer contains three distinct parts including core, building blocks and branching units or surface functional groups. These structures provide a lot of opportunities in the pharmaceutical field, particularly for novel drug development. In this review, a brief summary of different biomedical applications of peptide dendrimers is presented, and peptide dendrimers as active pharmaceutical ingredients and drug delivery carriers are discussed. Applications of peptide dendrimers in vaccines and diagnostic tools are also presented, in brief. Generally, peptide dendrimers are promising biomaterials with high evolution rate for clinical and non-clinical applications in medicine.

Bicyclic peptides: types, synthesis and applications.

Bicyclic peptides form one of the most promising platforms for drug development owing to their biocompatibility, similarity and chemical diversity to proteins, and they are considered as a possible practical tool in various therapeutic and diagnostic applications. Bicyclic peptides are known to have the capability of being employed as an effective alternative to complex molecules, such as antibodies, or small molecules. This review provides a summary of the recent progress on the types, synthesis and applications of bicyclic peptides. More specifically, natural and synthetic bicyclic peptides are introduced with their different production methods and relevant applications, including drug targeting, imaging and diagnosis. Their uses as antimicrobial agents, as well as the therapeutic functions of different bicyclic peptides, are also discussed.

Optimization of Key Factors in Serum Free Medium for Production of Human Recombinant GM-CSF Using Response Surface Methodology.

Researchers add serum to a classical medium at concentrations of 5 to 10% (v/v) to grow cells in-vitro culture media. Unfortunately, serum is a poorly defined culture medium component as its composition can vary considerably while serum-free cell culture media are an excellent alternative to standard serum-containing media and offer several major advantages. Advantages of using serum-free media include a lower risk of infectious agents, lower risk of interfering components, less contaminant, avoids ethical issues. According to previous studies insulin, selenium, transferrin and glucose are important component of serum that affect cell growth. In the present study, we optimized amount of these factors in order to serum free culture medium fabrication. Response surface methodology (RSM) was employed for optimization of key factors in serum free medium to enhance recombinant human GM-CSF (rhGM-CSF) production in CHO cell line. Four important process parameters including insulin concentration (0-2 g/L), transferrin concentration (0-1 g/L), selenium concentration (0-0.001 g/L) and glucose concentration (0-5 g/L) were optimized to obtain the best response of rhGM-CSF production using the statistical Box-Behnken design. The experimental data obtained were analyzed by analysis of variance (ANOVA) and fitted to a second-order polynomial equation using multiple regression analysis. Numerical optimization applying desirability function was used to identify the optimum conditions for maximum production of rhGM-CSF. The optimum conditions were found to be insulin concentration = 1.1 g/L, transferrin concentration = 0.545 g/L, selenium concentration = 0.000724 g/L and glucose = 1. 4 g/L. Maximum rhGM-CSF production was found to be 3.5 g/L.

Effect of Acyl Homoserine Lactone on Recombinant Production of Human Insulin-like Growth Factor-1 in Batch Culture of Escherichia coli.

BACKGROUND: IGF-I as a human growth factor produced in Escherichia coli is a single, non-glycosylated, polypeptide chain containing 70 amino acids and having a molecular mass of 7.6 kDa. Up to now, E. coli expression system has been widely used as the host to produce rhIGF-1 with high yields. Acyl Homoserine Lactones (AHLs) are intercellular signaling molecules used in quorum sensing by Gram-negative bacteria. Quorum sensing is a cell density-dependent gene regulation process that allows bacterial cells to express specific genes only when signaling molecules reach the sufficient concentration. OBJECTIVE: For the first time, this study focuses on the N-hexanoyl-L- Homoserine Lactone (HHL) activity on increasing the cell growth and rh-IGF-1concentration in batch culture of E. coli. METHOD: The maximum production of rhIGF-I was previously optimized in 32y culture medium at 32°C with 0.05 mM IPTG as inducer and 10 g/l glucose concentration. Under this condition, different amounts of HHL (0.001 µg/ml, 1 µg/ml, and 100µg/ml) were evaluated as an inducer for IGF-1 production. RESULTS: Generally, with increasing of HHL concentration, an increase in dry cell weight (2.45 mg/ml to 4.63 mg/ml) and IGF-I expression level (0.4 mg/ml to 0.77 mg/ml) was observed. CONCLUSION: HHL or other types of AHLs can be considered as protein production inducer in bacterial expression systems through the quorum sensing pathways.

Anti-Cancer Drug Delivery Using Carbohydrate-Based Polymers.

Polymeric drug delivery systems in the form of nanocarriers are the most interesting vehicles in anticancer therapy. Among different types of biocompatible polymers, carbohydrate-based polymers or polysaccharides are the most common natural polymers with complex structures consisting of long chains of monosaccharide or disaccharide units bound by glycosidic linkages. Their appealing properties such as availability, biocompatibility, biodegradability, low toxicity, high chemical reactivity, facile chemical modification and low cost led to their extensive applications in biomedical and pharmaceutical fields including development of nano-vehicles for delivery of anti-cancer therapeutic agents. Generally, reducing systemic toxicity, increasing short half-lives and tumor localization of agents are the top priorities for a successful cancer therapy. Polysaccharide-based or - coated nanosystems with respect to their advantageous features as well as accumulation in tumor tissue due to enhanced permeation and retention (EPR) effect can provide promising carrier systems for the delivery of noblest impressive agents. Most challenging factor in cancer therapy was the toxicity of anti-cancer therapeutic agents for normal cells and therefore, targeted delivery of these drugs to the site of action can be considered as an interesting therapeutic strategy. In this regard, several polysaccharides exhibited selective affinity for specific cell types, and so they can act as a targeting agent in drug delivery systems. Accordingly, different aspects of polysaccharide applications in cancer treatment or diagnosis were reviewed in this paper. In this regard, after a brief introduction of polysaccharide structure and its importance, the pharmaceutical usage of carbohydrate-based polymers was considered according to the identity of accompanying active pharmaceutical agents. It was also presented that the carbohydrate based polymers have been extensively considered as promising materials in the design of efficient nanocarriers for anti-cancer biopharmaceuticals including peptide and proteins or nucleic acid-based therapeutics. Then, the importance of various polysaccharide co-polymers in the drug delivery approaches was illustrated.

Nanobodies As Novel Agents for Targeting Angiogenesis in Solid Cancers.

Solid cancers are dependent on angiogenesis for sustenance. The FDA approval of Bevacizumab in 2004 inspired many scientists to develop more inhibitors of angiogenesis. Although several monoclonal antibodies (mAbs) are being administered to successfully combat various pathologies, the complexity and large size of mAbs seem to narrow the therapeutic applications. To improve the performance of cancer therapeutics, including those blocking tumor angiogenesis, attractive strategies such as miniaturization of the antibodies have been introduced. Nanobodies (Nbs), small single-domain antigen-binding antibody fragments, are becoming promising therapeutic and diagnostic proteins in oncology due to their favorable unique structural and functional properties. This review focuses on the potential and state of the art of Nbs to inhibit the angiogenic process for therapy and the use of labeled Nbs for non-invasive in vivo imaging of the tumors.

Targeted cancer therapy through antibody fragments-decorated nanomedicines.

Active targeting in cancer nanomedicine, for improved delivery of agents and diagnose, has been reviewed as a successful way for facilitating active uptake of theranostic agents by the tumor cells. The application of a targeting moiety in the targeted carrier complexes can play an important role in differentiating between tumor and healthy tissues. The pharmaceutical carriers, as main part of complexes, can be polymeric nanoparticles, micelles, liposomes, nanogels and carbon nanotubes. The antibodies are among the natural ligands with highest affinity and specificity to target pharmaceutical nanoparticle conjugates. However, the limitations, such as size and long circulating half-lives, hinder reproducible manufacture in clinical studies. Therefore, novel approaches have moved towards minimizing and engineering conventional antibodies as fragments like scFv, Fab, nanobody, bispecific antibody, bifunctional antibody, diabody and minibody preserving their functional potential. Different formats of antibody fragments have been reviewed in this literature update, in terms of structure and function, as smart ligands in cancer diagnosis and therapy of tumor cells.