In vitro and in vivo effects of polyhaemoglobin-tyrosinase on murine B16F10 melanoma

Tyrosinase-Loaded Multicompartment Microreactor toward Melanoma Depletion

Melanoma is malignant skin cancer occurring with increasing prevalence with no effective treatment. A unique feature of melanoma cells is that they require higher concentrations of ltyrosine (l-tyr) for expansion than normal cells. As such, it has been demonstrated that dietary l-tyr restriction lowers systemic l-tyr and suppresses melanoma advancement in mice. Unfortunately, this diet is not well tolerated by humans. An alternative approach to impede melanoma progression will be to administer the enzyme tyrosinase (TYR), which converts l-tyr into melanin. Herein, a multicompartment carrier consisting of a polymer shell entrapping thousands of liposomes is employed to act as a microreactor depleting l-tyr in the presence of melanoma cells. It is shown that the TYR enzyme can be incorporated within the liposomal subunits with preserved catalytic activity. Aiming to mimic the dynamic environment at the tumor site, l-tyr conversion is conducted by co-culturing melanoma cells and microreactors in a microfluidic setup with applied intratumor shear stress. It is demonstrated that the microreactors are concurrently depleting l-tyr, which translates into inhibited melanoma cell growth. Thus, the first microreactor where the depletion of a substrate translates into antitumor properties in vitro is reported.

Self-Monitoring Artificial Red Cells with Sufficient Oxygen Supply for Enhanced Photodynamic Therapy

Photodynamic therapy has been increasingly applied in clinical cancer treatments. However, native hypoxic tumoural microenvironment and lacking oxygen supply are the major barriers hindering photodynamic reactions. To solve this problem, we have developed biomimetic artificial red cells by loading complexes of oxygen-carrier (hemoglobin) and photosensitizer (indocyanine green) for boosted photodynamic strategy. Such nanosystem provides a coupling structure with stable self-oxygen supply and acting as an ideal fluorescent/photoacoustic imaging probe, dynamically monitoring the nanoparticle biodistribution and the treatment of PDT. Upon exposure to near-infrared laser, the remote-triggered photosensitizer generates massive cytotoxic reactive oxygen species (ROS) with sufficient oxygen supply. Importantly, hemoglobin is simultaneously oxidized into the more active and resident ferryl-hemoglobin leading to persistent cytotoxicity. ROS and ferryl-hemoglobin synergistically trigger the oxidative damage of xenograft tumour resulting in complete suppression. The artificial red cells with self-monitoring and boosted photodynamic efficacy could serve as a versatile theranostic platform.

Nanobiotechnological Nanocapsules Containing Polyhemoglobin-Tyrosinase: Effects on Murine B16F10 Melanoma Cell Proliferation and Attachment

We have reported previously that daily intravenous infusions of a soluble nanobiotechnological complex, polyhemoglobin-tyrosinase [polyHb-Tyr], can suppress the growth of murine B16F10 melanoma in a mouse model. In order to avoid the need for daily intravenous injections, we have now extended this further as follows. We have prepared two types of biodegradable nanocapsules containing [polyHb-Tyr]. One type is to increase the circulation time and decrease the frequency of injection and is based on polyethyleneglycol-polylactic acid (PEG-PLA) nanocapsules containing [polyHb-Tyr]. The other type is to allow for intratumoural or local injection and is based on polylactic acid (PLA) nanocapsules containing [polyHb-Tyr]. Cell culture studies show that it can inhibit the proliferation of murine B16F10 melanoma cells in the “proliferation model”. It can also inhibit the attachment of murine B16F10 melanoma cells in the “attachment model.” This could be due to the action of tyrosinase on the depletion of tyrosine or the toxic effect of tyrosine metabolites. The other component, polyhemoglobin (polyHb), plays a smaller role in nanocapsules containing [polyHb-Tyr], and this is most likely by its depletion of nitric oxide needed for melanoma cell growth.

From artificial red blood cells, oxygen carriers, and oxygen therapeutics to artificial cells, nanomedicine, and beyond

The first experimental artificial red blood cells have all three major functions of red blood cells (rbc). However, the first practical one is a simple polyhemoglobin (PolyHb) that only has an oxygen-carrying function. This is now in routine clinical use in South Africa and Russia. An oxygen carrier with antioxidant functions, PolyHb-catalase-superoxide dismutase, can fulfill two of the three functions of rbc. Even more complete is one with all three functions of rbc in the form of PolyHb-catalase-superoxide dismutase-carbonic anhydrase. The most advanced ones are nanodimension artificial rbc with either PEG-lipid membrane or PEG-PLA polymer membrane. Extensions into oxygen therapeutics include a PolyHb-tyrosinase that suppresses the growth of melanoma in a mice model. Another is a PolyHb-fibrinogen that is an oxygen carrier with platelet-like function. Research has now extended well beyond the original research on artificial rbc into many areas of artificial cells. These include nanoparticles, nanotubules, lipid vesicles, liposomes, polymer-tethered lipid vesicles, polymersomes, microcapsules, bioencapsulation, nanocapules, macroencapsulation, synthetic cells, and others. These are being used in nanotechnology, nanomedicine, regenerative medicine, enzyme/gene therapy, cell/stem cell therapy, biotechnology, drug delivery, hemoperfusion, nanosensers, and even by some groups in agriculture, industry, aquatic culture, nanocomputers, and nanorobotics.

PEG-PLA Nanocapsules Containing a Nanobiotechnological Complex of Polyhemoglobin-Tyrosinase for the Depletion of Tyrosine in Melanoma: Preparation and In Vitro Characterisation

Poly (ethylene glycol)-poly (lactic acid) block-copolymer (PEG-PLA) was optimized and characterized using H-NMR spectrum and DSC thermogram. This was then used for the preparation of PEG-PLA nanocapsules containing polyhemoglobin-tyrosinase. Transmission electron microscopic and scanning electron microscopic studies showed round and non-aggregated nanocapsules with a PEG halo around each nanocapsule. Dynamic Light Scattering showed that the Z-average diameter was 65.2 ± 0.5 nm (mean ± SEM) and the polydispersity index was 0.262 ± 0.002. Factors controlling the diameters included the stirring speed of the reaction mixture and the size of the PLA block in the PEG-PLA copolymer. At the body temperature of 37oC, free tyrosinase lost all its enzyme activity after 8 hours. However, Polyhemoglobin-tyrosinase nanocapcules retained 80% of its initial activity after 8 hours. This paper contains the first part of our work on the preparation and in vitro characterisation of PEG-PLA Polyhemoglobin-tyrosinase nanocapsules. Preliminary result in rats shows that 1 intravenous injection lowers the systemic tyrosine level to 10-13% after 5 minutes. The result of the detailed in vitro study and the preliminary animal study in have led to our ongoing detailed animal research to be reported in subsequent papers.

Polymer/hemoglobin assemblies: biodegradable oxygen carriers for artificial red blood cells

In routine clinical procedures, blood transfusion is now suffering from the defects of the blood products, like cross-matching, short storage time and virus infection. Various blood substitutes have been designed by researchers through continual efforts. With recent progress in nanotechnology, new types of artificial red blood cells with cellular structure are available. This article aims to describe some artificial red blood cells which encapsulate or conjugate hemoglobin molecules through various approaches, especially the nanoscale self-assembly technique, to mitigate the adverse effects of free hemoglobin molecules. These types of artificial red blood cell systems, which make use of biodegradable polymers as matrix materials, show advantages over the traditional types.

Blood replacement with nanobiotechnologically engineered hemoglobin and hemoglobin nanocapsules

Unlike donor red blood cells (RBCs), blood substitutes can be treated to remove infective agents and can be used on the spot or in the ambulance in emergency without the time-consuming typing and cross-matching. Donor RBC requires storage at 4 degrees and is only good for 42 days, but blood substitutes can be stored for much longer time. For example, a bovine polyhemoglobin (PolyHb) can be stored at room temperature for more than 1 year. It has been shown as far back as 1957 that artificial RBC can be prepared with ultrathin polymer membranes of nanodimension thickness. To increase the circulation time, the first-generation engineered hemoglobin (Hb) is formed by using glutaraldehyde to crosslink Hb into soluble nanodimension PolyHb that has been tested clinically in patients. Further extension includes conjugated Hb, intramolecularly crosslinked Hb and recombinant Hb. For certain clinical uses, in addition to engineered Hb, we also need antioxidants to remove oxygen radicals to prevent injury from ischemia reperfusion. Thus, we use nanobiotechnology to prepare second-generation engineered Hb by assembling Hb together with superoxide dismutase (SOD) and catalase (CAT) to form a nanodimension soluble complex of polyhemoglobin (PolyHb)-CAT-SOD. A third generation system is to prepare nanodimension complete artificial RBCs that can circulate for sufficient length of time after infusion. One approach uses lipid vesicles to encapsulate hemoglobin (Hb). Another approach is to use biodegradable polymer-like polylactic acid or a copolymer of polyethylene glycol-polylactide (PEG-PLA) to form the membrane of nanodimension complete artificial RBC (www.artcell.mcgill.ca).

Evolution of Artificial Cells Using Nanobiotechnology of Hemoglobin Based RBC Blood Substitute as an Example

The original artificial red blood cells have evolved into oxygen carriers in the form of polyhemoglobin and conjugated hemoglobin. Clinical conditions requiring only oxygen carriers are responding well to these types of oxygen carriers without the need for a complete artificial red blood cell. For those conditions requiring more than just oxygen carriers, new generations of polyhemoglobin containing antioxidant enzymes are being developed. Though a complete artificial red blood cell comparable to red blood cell is still a dream, development in lipid membrane artificial red blood cells and biodegradable polymeric nano artificial red blood cells are steps towards this possibility. The many years of neglect on basic research in the area of blood substitutes have resulted in the lack of important basic knowledge needed for the rapid development of blood substitutes suitable for clinical use. This is further hampered by the mistaken conception that blood substitute is a single entity. We need to look at blood substitutes as consisting of progressively more complicated entities, e.g. oxygen carriers, oxygen carriers with antioxidant activity, and complete red blood cell substitutes. Each of these entities is not applicable to all clinical conditions, but is suitable for specific applications.

Nanobiotechnology for hemoglobin-based blood substitutes

Nanobiotechnology is the assembling of biological molecules into nanodimension complexes. This has been used for the preparation of polyhemoglobin formed by the assembling of hemoglobin molecules into a soluble nanodimension complex. New generations of this approach include the nanobiotechnological assembly of hemoglobin, catalase, and superoxide dismutase into a soluble nanodimension complex. This acts as an oxygen carrier and an antioxidant for those conditions with potential for ischemiareperfusion injuries. Another recent novel approach is the assembling of hemoglobin and fibrinogen into a soluble nanodimension polyhemoglobin-fibrinogen complex that acts as an oxygen carrier with platelet-like activity. This is potentially useful in cases of extensive blood loss requiring massive replacement using blood substitutes, resulting in the need for the replacement of platelets and clotting factors. A further step is the preparation of nanodimension artificial red blood cells that contain hemoglobin and all the enzymes present in red blood cells.

Nanobiotechnological modification of hemoglobin and enzymes from this laboratory

Polyhemoglobin is formed by the nanobiotechnological assembling of hemoglobin molecules into soluble nanodimension complex. A further step involves the nanobiotechnological assembly of hemoglobin, catalase and superoxide dismutase into a soluble nanodimension complex. This acts both as oxygen carrier and antioxidant to prevent the oxidative effects of hemoglobin. A further step is the preparation of nanodimension artificial red blood cells that contain hemoglobin and all the enzymes present in red blood cells. Other approaches include a polyhemoglobin-fibrinogen that acts as an oxygen carrier with platelet-like activity, and a polyhemoglobin-tyrosinase to retard the growth of a fatal skin cancer, melanoma.

Blood substitutes based on nanobiotechnology

Stimulated by concerns of potential infective agents in donated blood, commercial enterprises have attempted to develop blood substitutes since the 1900s. After several years of development, a few of the many leads are showing promise. In this article, nanobiotechnological approaches that are now in phase III clinical trials are reviewed, followed by a discussion of how important basic knowledge gained is being used to develop new generations of blood substitutes based on nanobiotechnology.

TXM13 human melanoma cells: a novel source for the inhibition kinetics of human tyrosinase and for screening whitening agents

Research involving whitening agents requires several steps of experimentation, and the initial step is to test whitening agents with human melanocytes and those with human tyrosinase. Unfortunately, it takes a long time to gather human melanocytes, and these cells have some limitations when it comes to performing experiments, such as their passage difficulties and their cost. In this study, we suggest that the TXM13 human melanoma cells could be a useful cell candidate for studying human tyrosinase inhibition and depigmentation. We applied a tyrosinase inhibitor, such as dithioglycerine (DTGC), to validate the cell line's usefulness, and we tested the effect of DTGC on TXM13 melanogenesis. The results showed that human tyrosinase from TXM13 was appropriate, according to the inhibition kinetics, and that the conspicuous depigmentation of TXM13 occurred after DTGC treatment without downregulating the tyrosinase expression level. When taken together, our findings provide useful information regarding the use of the TXM13 melanoma cells for the development of whitening agents.Key words: TXM13, pigment cell, human tyrosinase, whitening agent.

Therapeutic applications of polymeric artificial cells

Polymeric artificial cells have the potential to be used for a wide variety of therapeutic applications, such as the encapsulation of transplanted islet cells to treat diabetic patients. Recent advances in biotechnology, molecular biology, nanotechnology and polymer chemistry are now opening up further exciting possibilities in this field. However, it is also recognized that there are several key obstacles to overcome in bringing such approaches into routine clinical use. This review describes the historical development and principles behind polymeric artificial cells, the present state of the art in their therapeutic application, and the promises and challenges for the future.

Hemoglobin-based Red Blood Cell Substitutes

Polyhemoglobin is already well into the final stages of clinical trials in humans with one approved for routine clinical use in South Africa. Conjugated hemoglobin is also in ongoing clinical trials. Meanwhile, recombinant Hb has been modified to modulate the effects of nitric oxide. Other systems contain antioxidant enzymes for those clinical applications that may have potential problems related to ischemia-reperfusion injuries. Other developments are based on hemoglobin-lipid vesicles and also the use of nanotechnology and biodegradable copolymers to prepare nanodimension artificial red blood cells containing hemoglobin and complex enzyme systems.