An innovative biologic system for photon-powered myocardium in the ischemic heart

Photosynthetic Bacteria: Light-Responsive Biomaterials for Anti-Tumor Photodynamic Therapy

Photodynamic therapy (PDT) is a promising noninvasive tumor treatment modality that relies on generating reactive oxygen species (ROS) and requires an adequate oxygen supply to the target tissue. However, hypoxia is a common feature of solid tumors and profoundly restricts the anti-tumor efficacy of PDT. In recent years, scholars have focused on exploring nanomaterial-based strategies for oxygen supplementation and integrating non-oxygen-consuming treatment approaches to overcome the hypoxic limitations of PDT. Some scholars have harnessed the photosynthetic oxygen production of cyanobacteria under light irradiation to overcome tumor hypoxia and engineered them as carriers of photosensitizers instead of inorganic nanomaterials, resulting in photosynthetic bacteria (PSB) attracting significant attention. Recent studies have shown that light-triggered PSB can exhibit additional properties, such as photosynthetic hydrogen production, ROS generation, and photothermal conversion, facilitating their use as promising light-responsive biomaterials for enhancing the anti-tumor efficacy of PDT. Therefore, understanding PSB can provide new insights and ideas for future research. This review mainly introduces the characteristics of PSB and recent research on light-triggered PSB in anti-tumor PDT to enrich our knowledge in this area. Finally, the challenges and prospects of using PSB to enhance the anti-tumor efficacy of PDT were also discussed.

Oxygenation by Intravascular Photosynthesis Reduces Kidney Damage During ex Vivo Preservation

Several clinical issues are associated with reduced oxygen delivery to tissues due to impaired vascular perfusion; moreover, organs procured for transplantation are subjected to severe hypoxia during preservation. Consequently, alternative tissue oxygenation is an active field in biomedical research where several innovative approaches have been recently proposed. Among these, intravascular photosynthesis represents a promising approach as it relies on the intrinsic capacity of certain microorganisms to produce oxygen upon illumination. In this context, this work aims at the development of photosynthetic perfusable solutions that could be applied to preserve organs for transplantation purposes. Our findings demonstrate that a biocompatible physiological solution containing the photosynthetic microalgae Chlamydomonas reinhardtii can fulfill the metabolic oxygen demand of rat kidney slices in vitro. Furthermore, intravascular administration of this solution does not induce tissue damage in the rat kidneys. Moreover, kidney slices obtained from these algae-perfused organs exhibited significantly improved preservation after 24 h of incubation in hypoxia while exposed to light, resulting in reduced tissue damage and enhanced metabolic status. Overall, the results presented here contribute to the development of alternative strategies for tissue oxygenation, supporting the use of perfusable photosynthetic solutions for organ preservation in transplantation.

Incorporation of photosynthetically active algal chloroplasts in cultured mammalian cells towards photosynthesis in animals

Chloroplasts are photosynthetic organelles that evolved through the endosymbiosis between cyanobacteria-like symbionts and hosts. Many studies have attempted to isolate intact chloroplasts to analyze their morphological characteristics and photosynthetic activity. Although several studies introduced isolated chloroplasts into the cells of different species, their photosynthetic activities have not been confirmed. In this study, we isolated photosynthetically active chloroplasts from the primitive red alga Cyanidioschyzon merolae and incorporated them in cultured mammalian cells via co-cultivation. The incorporated chloroplasts retained their thylakoid structure in intracellular vesicles and were maintained in the cytoplasm, surrounded by the mitochondria near the nucleus. Moreover, the incorporated chloroplasts maintained electron transport activity of photosystem II in cultured mammalian cells for at least 2 days after the incorporation. Our top-down synthetic biology-based approach may serve as a foundation for creating artificially photosynthetic animal cells.

Gas immnuo-nanomedicines fight cancers

Certain gas molecules, including hydrogen (H2), nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2S), oxygen (O2) and sulfur dioxide (SO2) exhibit significant biological functionalities that can modulate the immune response. Strategies pertaining to gas-based immune therapy have garnered considerable attention in recent years. Nevertheless, delivering various gas molecules precisely into tumors, which leads to enhanced anti-tumor immunotherapeutic effect, is still a main challenge. The advent of gas treatment modality with desirable immunotherapeutic efficiency has been made possible by the rapid development of nanotechnology, which even derives the concept of the gas immnuo-nanomedicines (GINMs). In light of the fact, we herein aim to furnish a cutting-edge review on the latest progress of GINMs. The underlying mechanisms of action for several gases utilized in cancer immunotherapy are initially outlined. Additionally, it provides a succinct overview of the current clinical landscape of gas therapy, and introduces GINMs specifically designed for cancer treatment based on immunotherapeutic principles across multiple strategies. Last but not least, we address the challenges and opportunities associated with GINMs, exploring the potential future developments and clinical applications of this innovative approach.

Towards chlorocytes for therapeutic intravascular photosynthesis

Aerobic metabolism relies on external oxygen production through photosynthesis and its subsequent transport into each cell of the body via the cardiorespiratory system. This mechanism has successfully evolved over millions of years, enabling animals to inhabit most environments on Earth. However, the insufficient oxygen supply leads to several clinical problems, ranging from non-healing wounds to tumor resistance to therapy. Given that photosynthetic microorganisms are capable of producing oxygen and removing carbon dioxide from the environment, over the last decade, several groups worldwide have proposed their potential use as an alternative tissue oxygenation approach. While most studies have demonstrated safety and efficacy after local tissue administration, recent studies have also suggested that systemic administration could trigger intravascular photosynthesis. If successful, the development of a new generation of circulating cells, known as chlorocytes, may partially replace the role of erythrocytes in gas exchange within the body, without relying on external supply and vascular flow. This work reviews the existing literature on local and systemic administration of photosynthetic microorganisms, highlighting the main challenges in the field and potential solutions to unleash the enormous potential clinical impact of chlorocytes and intravascular photosynthesis. KEY POINTS: • Circulating photosynthetic microorganisms could deliver oxygen to tissues • Microalgae and cyanobacteria have shown safety and efficacy for oxygen delivery • Several key challenges need to be addressed for the clinical success of chlorocytes.

Evaluation of the value of Synechococcus 7942 as a sensitizer for photo-sonodynamic therapy against breast cancer

This study was conducted to investigate the value of Synechococcus 7942 (Syne) as a sensitizer for photo-sonodynamic therapy (PSDT). Syne was characterized. The efficacy of Syne-mediated PSDT were verified in vitro (in 4T1 breast cancer cells) and in vivo (in a breast tumor-bearing mouse model). The safety of Syne-mediated PSDT was verified in vivo. Results indicated that Syne triggered the generation of oxygen and ROS during PSDT, thereby inducing cell death in 4T1 cells. Syne-mediated PSDT induced the death of tumor cells both in vitro and in vivo. The speed of tumor growth was delayed in animals receiving PSDT. Syne-mediated PSDT was more effective than photodynamic therapy or sonodynamic therapy alone. In addition, administration of a Syne monomer resulted in satisfactory tumor targeting. Syne-mediated PSDT affected neither the animal body weight nor the major organs, indicating satisfactory safety. Accordingly, Syne is an efficient, safe, and readily available sensitizer that is ideal for potential clinical use of PSDT to treat breast cancer. The findings of this study are useful for exploration of a novel sensitizer for PSDT, which might be a promising alternative therapy against breast cancer.

A serum-free culture medium production system by co-culture combining growth factor-secreting cells and L-lactate-assimilating cyanobacteria for sustainable cultured meat production

Large-scale production of cultured meat requires bulk culture medium containing growth-promoting proteins from animal serum. However, animal serum for mammalian cell culture is associated with high costs, ethical concerns, and contamination risks. Owing to its growth factor content, conditioned medium from rat liver epithelial RL34 cells can replace animal serum for myoblast proliferation. More seeded cells and longer culture periods are thought to yield higher growth factor levels, resulting in more effective muscle cell proliferation. However, RL34 cells can deplete nutrients and release harmful metabolites into the culture medium over time, potentially causing growth inhibition and apoptosis. This issue highlights the need for waste clearance during condition medium production. To address this issue, we introduced a lactate permease gene (lldP) and an L-lactate-to-pyruvate conversion enzyme gene (lldD) to generate a recombinant L-lactate-assimilating cyanobacterium Synechococcus sp. KC0110 strain. Transwell co-culture of this strain with RL34 cells exhibited a marked reduction in the levels of harmful metabolites, lactate and ammonium, while maintaining higher concentrations of glucose, pyruvate, and pyruvate-derived amino acids than those seen with RL34 cell monocultures. The co-culture medium supported myoblast proliferation without medium dilution or additional nutrients, which was attributed to the waste clearance and nutrient replenishment effects of the KC0110 strain. This culture system holds potential for the production of low-cost, and animal-free cultured meat.

Processed microalgae: green gold for tissue regeneration and repair

As novel biomedical materials, microalgae have garnered significant interest because of their ability to generate photosynthetic oxygen, their antioxidant activity, and their favorable biocompatibility. Many studies have concentrated on the hypoxia-alleviating effects of microalgae within tumor microenvironments. However, recent findings indicate that microalgae can significantly increase the regeneration of various tissues and organs. To augment microalgae's therapeutic efficacy and mitigate the limitations imposed by immune clearance, it is essential to process microalgae through various processing strategies. This review examines common microalgal species in biomedical applications, such as Chlorella, Chlamydomonas reinhardtii, diatoms, and Spirulina. This review outlines diverse processing methods, including microalgae extracts, microalgae‒nanodrug composite delivery systems, surface modifications, and living microalgae‒loaded hydrogels. It also discusses the latest developments in tissue repair using processed microalgae for skin, gastrointestinal, bone, cardiovascular, lung, nerve, and oral tissues. Furthermore, future directions are presented, and research gaps for processed microalgae are identified. Collectively, these insights may inform the innovation of processed microalgae for various uses and offer guidance for ongoing research in tissue repair.

Sonosynthetic Cyanobacteria Oxygenation for Self-Enhanced Tumor-Specific Treatment

Photosynthesis, essential for life on earth, sustains diverse processes by providing nutrition in plants and microorganisms. Especially, photosynthesis is increasingly applied in disease treatments, but its efficacy is substantially limited by the well-known low penetration depth of external light. Here, ultrasound-mediated photosynthesis is reported for enhanced sonodynamic tumor therapy using organic sonoafterglow (ultrasound-induced afterglow) nanoparticles combined with cyanobacteria, demonstrating the proof-of-concept sonosynthesis (sonoafterglow-induced photosynthesis) in cancer therapy. Chlorin e6, a typical small-molecule chlorine, is formulated into nanoparticles to stimulate cyanobacteria for sonosynthesis, which serves three roles, i.e., overcoming the tissue-penetration limitations of external light sources, reducing hypoxia, and acting as a sonosensitizer for in vivo tumor suppression. Furthermore, sonosynthetic oxygenation suppresses the expression of hypoxia-inducible factor 1α, leading to reduced stability of downstream SLC7A11 mRNA, which results in glutathione depletion and inactivation of glutathione peroxidase 4, thereby inducing ferroptosis of cancer cells. This study not only broadens the scope of microbial nanomedicine but also offers a distinct direction for sonosynthesis.

Biomedical engineering utilizing living photosynthetic cyanobacteria and microalgae: Current status and future prospects

Cyanobacteria are the only prokaryotes capable of performing oxygenic photosynthesis on Earth. Besides their traditional roles serving as primary producers, cyanobacteria also synthesize abundant secondary metabolites including carotenoids, alkaloids, peptides, which have been reported to possess medicinal potentials. More importantly, the advancement of synthetic biology technology has further expanded their potential biomedical applications especially using living/engineered cyanobacteria, providing promising and attractive strategies for future disease treatments. To improve the understanding and to facilitate future applications, this review aims to discuss the current status and future prospects of cyanobacterial-based biomedical engineering. Firstly, specific properties of cyanobacteria related with biomedical applications like their natural products of bioactive compounds and heavy metal adsorption were concluded. Subsequently, based on these properties of cyanobacteria, we discussed the progress of their applications in various disease models like hypoxia microenvironment alleviation, wound healing, drug delivery, and so on. Finally, the future prospects including further exploration of cyanobacteria secondary metabolites, the integration of bioactive compounds synthesized by cyanobacteria in situ with medical diagnosis and treatment, and the optimization of in vivo application were critically presented. The review will promote the studies related with cyanobacteria-based biomedical engineering and its practical application in clinical trials in the future.

Chemically Programmed Hydrogels for Spatiotemporal Modulation of the Cardiac Pathological Microenvironment

After myocardial infarction (MI), sustained ischemic events induce pathological microenvironments characterized by ischemia-hypoxia, oxidative stress, inflammatory responses, matrix remodeling, and fibrous scarring. Conventional clinical therapies lack spatially targeted and temporally responsive modulation of the infarct microenvironment, leading to limited myocardial repair. Engineered hydrogels have a chemically programmed toolbox for minimally invasive localization of the pathological microenvironment and personalized responsive modulation over different pathological periods. Chemically programmed strategies for crosslinking interactions, interfacial binding, and topological microstructures in hydrogels enable minimally invasive implantation and in situ integration tailored to the myocardium. This enhances substance exchange and signal interactions within the infarcted microenvironment. Programmed responsive polymer networks, intelligent micro/nanoplatforms, and biological therapeutic cues contribute to the formation of microenvironment-modulated hydrogels with precise targeting, spatiotemporal control, and on-demand feedback. Therefore, this review summarizes the features of the MI microenvironment and chemically programmed schemes for hydrogels to conform, integrate, and modulate the cardiac pathological microenvironment. Chemically programmed strategies for oxygen-generating, antioxidant, anti-inflammatory, provascular, and electrointegrated hydrogels to stimulate iterative and translational cardiac tissue engineering are discussed.

Biomedical application of microalgal-biomaterials hybrid system

Microalgae are a group of microorganisms containing chlorophyll A, which are highly photosynthetic and rich in nutrients. And they can produce multiple bioactive substances (peptides, proteins, polysaccharides, and fatty acids) for biomedical applications. Despite the unique advantages of microalgae-based biotherapy, the insufficient treatment efficiency limits its further application. With the development of nanotechnology, the combination of microalgae and biomaterials can improve therapeutic efficacies, which has attracted increasing attention. In this microalgal-biomaterials hybrid system, biomaterials with excellent optical and magnetic properties play an important role in biological therapy. Microalgae, as a natural vehicle, can increase oxygen content and alleviate hypoxia in diseased areas, further enhancing therapeutic effects. In this review, the synergistic therapeutic effects of microalgal-biomaterials hybrid system in different diseases (cancer, myocardial infarction, ischemia stroke, chronic infection, and intestinal diseases) are comprehensively summarized.

Engineered Cyanobacteria-Based Living Materials for Bioremediation of Heavy Metals Both In Vitro and In Vivo

The pollution caused by heavy metals (HMs) represents a global concern due to their serious environmental threat. Photosynthetic cyanobacteria have a natural niche and the ability to remediate HMs such as cadmium. However, their practical application is hindered by a low tolerance to HMs and issues related to recycling. In response to these challenges, this study focuses on the development and evaluation of engineered cyanobacteria-based living materials for HMs bioremediation. Genes encoding phytochelatins (PCSs) and metallothioneins (MTs) were introduced into the model cyanobacterium Synechocystis sp. PCC 6803, creating PM/6803. The strain exhibited improved tolerance to multiple HMs and effectively removed a combination of Cd2+, Zn2+, and Cu2+. Using Cd2+ as a representative, PM/6803 achieved a bioremediation rate of approximately 21 μg of Cd2+/OD750 under the given test conditions. To facilitate its controllable application, PM/6803 was encapsulated using sodium alginate-based hydrogels (PM/6803@SA) to create "living materials" with different shapes. This system was feasible, biocompatible, and effective for removing Cd2+ under simulated conditions of zebrafish and mice models. Briefly, in vitro application of PM/6803@SA efficiently rescued zebrafish from polluted water containing Cd2+, while in vivo use of PM/6803@SA significantly decreased the Cd2+ content in mice bodies and restored their active behavior. The study offers feasible strategies for HMs bioremediation using the interesting biomaterials of engineered cyanobacteria both in vitro and in vivo.

Hypoxic environment of wounds and photosynthesis-based oxygen therapy

The hypoxic environment is among the most important factors that complicates the healing of chronic wounds, such as venous leg ulcers, pressure injuries and diabetic foot ulcers, which seriously affects the quality of life of patients. Various oxygen supply treatments are used in clinical practice to improve the hypoxic environment at the wound site. However, problems still occur, such as insufficient oxygen supply, short oxygen infusion time and potential biosafety risks. In recent years, artificial photosynthetic systems have become a research hotspot in the fields of materials and energy. Photosynthesis is expected to improve the oxygen level at wound sites and promote wound healing because the method provides a continuous oxygen supply and has good biosafety. In this paper, oxygen treatment methods for wounds are reviewed, and the oxygen supply principle and construction of artificial photosynthesis systems are described. Finally, research progress on the photosynthetic oxygen production system to promote wound healing is summarized.

Plants as a cost-effective source for customizable photosynthetic wound dressings: A proof of concept study

Oxygen is essential for tissue regeneration, playing a crucial role in several processes, including cell metabolism and immune response. Therefore, the delivery of oxygen to wounds is an active field of research, and recent studies have highlighted the potential use of photosynthetic biomaterials as alternative oxygenation approach. However, while plants have traditionally been used to enhance tissue regeneration, their potential to produce and deliver local oxygen to wounds has not yet been explored. Hence, in this work we studied the oxygen-releasing capacity of Marchantia polymorpha explants, showing their capacity to release oxygen under different illumination settings and temperatures. Moreover, co-culture experiments revealed that the presence of these explants had no adverse effects on the viability and morphology of fibroblasts in vitro, nor on the viability of zebrafish larvae in vivo. Furthermore, oxygraphy assays demonstrate that these explants could fulfill the oxygen metabolic requirements of zebrafish larvae and freshly isolated skin biopsies ex vivo. Finally, the biocompatibility of explants was confirmed through a human skin irritation test conducted in healthy volunteers following the ISO-10993-10-2010. This proof-of-concept study provides valuable scientific insights, proposing the potential use of freshly isolated plants as biocompatible low-cost oxygen delivery systems for wound healing and tissue regeneration.

Advances in Engineered Nanoparticles for the Treatment of Ischemic Stroke by Enhancing Angiogenesis

Angiogenesis, or the formation of new blood vessels, is a natural defensive mechanism that aids in the restoration of oxygen and nutrition delivery to injured brain tissue after an ischemic stroke. Angiogenesis, by increasing vessel development, may maintain brain perfusion, enabling neuronal survival, brain plasticity, and neurologic recovery. Induction of angiogenesis and the formation of new vessels aid in neurorepair processes such as neurogenesis and synaptogenesis. Advanced nano drug delivery systems hold promise for treatment stroke by facilitating efficient transportation across the the blood-brain barrier and maintaining optimal drug concentrations. Nanoparticle has recently been shown to greatly boost angiogenesis and decrease vascular permeability, as well as improve neuroplasticity and neurological recovery after ischemic stroke. We describe current breakthroughs in the development of nanoparticle-based treatments for better angiogenesis therapy for ischemic stroke employing polymeric nanoparticles, liposomes, inorganic nanoparticles, and biomimetic nanoparticles in this study. We outline new nanoparticles in detail, review the hurdles and strategies for conveying nanoparticle to lesions, and demonstrate the most recent advances in nanoparticle in angiogenesis for stroke treatment.

Biocompatibility of Synechococcus sp. PCC 7002 with Human Dermal Cells In Vitro

Being the green gold of the future, cyanobacteria have recently attracted considerable interest worldwide. This study investigates the adaptability and biocompatibility of the cyanobacterial strain Synechococcus sp. PCC 7002 with human dermal cells, focusing on its potential application in biomedical contexts. First, we investigated the adaptability of Synechococcus PCC 7002 bacteria to human cell culture conditions. Next, we evaluated the biocompatibility of cyanobacteria with common dermal cells, like 3T3 fibroblasts and HaCaT keratinocytes. Therefore, cells were directly and indirectly cocultured with the corresponding cells, and we measured metabolic activity (AlamarBlue assay) and proliferation (cell count and PicoGreen assay). The lactate dehydrogenase (LDH) assay was performed to determine the cytotoxic effect of cyanobacteria and their nutrition medium on human dermal cells. The cyanobacteria exhibited exponential growth under conventional human cell culture conditions, with the temperature and medium composition not affecting their viability. In addition, the effect of illumination on the proliferation capacity was investigated, showing a significant impact of light exposure on bacterial growth. The measured oxygen production under hypoxic conditions demonstrated a sufficient oxygen supply for further tissue engineering approaches depending on the number of bacteria. There were no significant adverse effects on human cell viability and growth under coculture conditions, whereas the LDH assay assessed signs of cytotoxicity regarding 3T3 fibroblasts after 2 days of coculturing. These negative effects were dismissed after 4 days. The findings highlight the potential of Synechococcus sp. PCC 7002 for integration into biomedical approaches. We found no cytotoxicity of cyanobacteria on 3T3 fibroblasts and HaCaT keratinocytes, thus paving the way for further in vivo studies to assess long-term effects and systemic reactions.

In Situ Formed Microalgae-Integrated Living Hydrogel for Enhanced Tumor Starvation Therapy and Immunotherapy through Photosynthetic Oxygenation

The effectiveness of various cancer therapies for solid tumors is substantially limited by the highly hypoxic tumor microenvironment (TME). Here, a microalgae-integrated living hydrogel (ACG gel) is developed to concurrently enhance hypoxia-constrained tumor starvation therapy and immunotherapy. The ACG gel is formed in situ following intratumoral injection of a biohybrid fluid composed of alginate, Chlorella sorokiniana, and glucose oxidase, facilitated by the crossing-linking between divalent ions within tumors and alginate. The microalgae Chlorella sorokiniana embedded in ACG gel generate abundant oxygen through photosynthesis, enhancing glucose oxidase-catalyzed glucose consumption and shifting the TME from immunosuppressive to immunopermissive status, thus reducing the tumor cell energy supply and boosting antitumor immunity. In murine 4T1 tumor models, the ACG gel significantly suppresses tumor growth and effectively prevents postoperative tumor recurrence. This study, leveraging microalgae as natural oxygenerators, provides a versatile and universal strategy for the development of oxygen-dependent tumor therapies.

In-situ-sprayed therapeutic hydrogel for oxygen-actuated Janus regulation of postsurgical tumor recurrence/metastasis and wound healing

Surgery is the mainstay of treatment modality for malignant melanoma. However, the deteriorative hypoxic microenvironment after surgery is recognized as a stemming cause for tumor recurrence/metastasis and delayed wound healing. Here we design and construct a sprayable therapeutic hydrogel (HIL@Z/P/H) encapsulating tumor-targeted nanodrug and photosynthetic cyanobacteria (PCC 7942) to prevent tumor recurrence/metastasis while promote wound healing. In a postsurgical B16F10 melanoma model in female mice, the nanodrug can disrupt cellular redox homeostasis via the photodynamic therapy-induced cascade reactions within tumor cells. Besides, the photosynthetically generated O2 by PCC 7942 can not only potentiate the oxidative stress-triggered cell death to prevent local recurrence of residual tumor cells, but also block the signaling pathway of hypoxia-inducible factor 1α to inhibit their distant metastasis. Furthermore, the long-lasting O2 supply and PCC 7942-secreted extracellular vesicles can jointly promote angiogenesis and accelerate the wound healing process. Taken together, the developed HIL@Z/P/H capable of preventing tumor recurrence/metastasis while promoting wound healing shows great application potential for postsurgical cancer therapy.

A codon-based live-cell biomonitoring system for assessing intracellular phenylalanine bioavailability in cyanobacteria

Phenylalanine, as an essential aromatic amino acid, is not only needed for protein and vital molecules such as neurotransmitter and hormone synthesis but also a substrate for the biosynthesis of phenylpropanoids and various bioactive compounds. The metabolism of phenylalanine is dynamic and transitory, which would otherwise inhibit cell growth. Therefore, it is challenging and imperative to monitor intracellular phenylalanine bioavailability in real time, which has great significance for evaluating the effectiveness of introducing pathway-specific genetic modifications to enhance phenylalanine generation. In this study, we proposed a live-cell biomonitoring system to assess phenylalanine bioavailability in real time in cyanobacteria based on codon degeneracy and species-specific usage bias. The biomonitoring system was generated through genetic modification of phenylalanine codons in the chloramphenicol antibiotic resistance gene to wholly preferred and rare codons, in combination with an orthogonal constitutive promoter Trc to express these genes. Cyanobacterial cells equipped with a preferred codon-based gene showed a significant growth advantage over those with rare codons under antibiotic pressure, while the delayed growth caused by rare codon-based genes could be rescued by supplementing phenylalanine in the cultivation medium. Increasing intracellular phenylalanine bioavailability could promote rare codon-based gene containing cell growth to a similar level as wild-type strains harboring preferred codon-based gene, providing a live-cell visualized screening method to relatively define phenylalanine content from either random mutation libraries or pathway-specific engineering cyanobacterial chassis before conducting labor-intensive quantitative measurements.

Microalgae-material hybrid for enhanced photosynthetic energy conversion: a promising path towards carbon neutrality

Photosynthetic energy conversion for high-energy chemicals generation is one of the most viable solutions in the quest for sustainable energy towards carbon neutrality. Microalgae are fascinating photosynthetic organisms, which can directly convert solar energy into chemical energy and electrical energy. However, microalgal photosynthetic energy has not yet been applied on a large scale due to the limitation of their own characteristics. Researchers have been inspired to couple microalgae with synthetic materials via biomimetic assembly and the resulting microalgae-material hybrids have become more robust and even perform new functions. In the past decade, great progress has been made in microalgae-material hybrids, such as photosynthetic carbon dioxide fixation, photosynthetic hydrogen production, photoelectrochemical energy conversion and even biochemical energy conversion for biomedical therapy. The microalgae-material hybrid offers opportunities to promote artificially enhanced photosynthesis research and synchronously inspires investigation of biotic-abiotic interface manipulation. This review summarizes current construction methods of microalgae-material hybrids and highlights their implication in energy and health. Moreover, we discuss the current problems and future challenges for microalgae-material hybrids and the outlook for their development and applications. This review will provide inspiration for the rational design of the microalgae-based semi-natural biohybrid and further promote the disciplinary fusion of material science and biological science.

Microalgae share key features with human erythrocytes and can safely circulate through the vascular system in mice

As animal cells cannot produce oxygen, erythrocytes are responsible for gas interchange, being able to capture and deliver oxygen upon tissue request. Interestingly, several other cells in nature produce oxygen by photosynthesis, raising the question of whether they could circulate within the vascular networks, acting as an alternative source for oxygen delivery. To address this long-term goal, here some physical and mechanical features of the photosynthetic microalga Chlamydomona reinhardtii were studied and compared with erythrocytes, revealing that both exhibit similar size and rheological properties. Moreover, key biocompatibility aspects of the microalgae were evaluated in vitro and in vivo, showing that C. reinhardtii can be co-cultured with endothelial cells, without affecting each other's morphology and viability. Moreover, short-term systemic perfusion of the microalgae showed a thoroughly intravascular distribution in mice. Finally, the systemic injection of high numbers of microalgae did not trigger deleterious responses in living mice. Altogether, this work provides key scientific insights to support the notion that photosynthetic oxygenation could be achieved by circulating microalgae, representing another important step towards human photosynthesis. KEY POINTS: • C. reinhardtii and endothelial cells are biocompatible in vitro. • C. reinhardtii distribute throughout the entire vasculature after mice perfusion. • C. reinhardtii do not trigger deleterious responses after injection in mice.

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

Integrated cascade catalysis of microalgal bioenzyme and inorganic nanozyme for anti-inflammation therapy

Combinations of multiple enzymes for cascade catalysis have been widely applied in biomedicine, but the integration of a natural bioenzyme with an inorganic nanozyme is less developed. Inspired by the abundant content of superoxide dismutase (SOD) in Spirulina platensis (SP), we establish an integrated cascade catalysis for anti-inflammation therapy by decorating catalase (CAT)-biomimetic ceria nanoparticles (CeO₂) onto the SP surface via electrostatic interaction to build microalgae-based biohybrids. The biohybrids exhibit combined catalytical competence for preferentially transforming superoxide anion radicals (O₂˙^-) to hydrogen peroxide (H₂O₂), and subsequently catalyzing H₂O₂ disproportionation to water and oxygen. In ulcerative colitis and Crohn's disease, the biohybrids reveal a satisfactory therapeutic effect owing to the synergistic reactive oxygen species (ROS)-scavenging capacity, suggesting a new train of thought for enzyme-based biomedical application.

Microfluidic encapsulation of photosynthetic cyanobacteria in hydrogel microparticles augments oxygen delivery to rescue ischemic myocardium

Cardiovascular disease, primarily caused by coronary artery disease, is the leading cause of death in the United States. While standard clinical interventions have improved patient outcomes, mortality rates associated with eventual heart failure still represent a clinical challenge. Macrorevascularization techniques inadequately address the microvascular perfusion deficits that persist beyond primary and secondary interventions. In this work, we investigate a photosynthetic oxygen delivery system that rescues the myocardium following acute ischemia. Using a simple microfluidic system, we encapsulated Synechococcus elongatus into alginate hydrogel microparticles (HMPs), which photosynthetically deliver oxygen to ischemic tissue in the absence of blood flow. We demonstrate that HMPs improve the viability of S. elongatus during the injection process and allow for simple oxygen diffusion. Adult male Wistar rats (n = 45) underwent sham surgery, acute ischemia reperfusion surgery, or a chronic ischemia reperfusion surgery, followed by injection of phosphate buffered saline (PBS), S. elongatus suspended in PBS, HMPs, or S. elongatus encapsulated in HMPs. Treatment with S. elongatus-HMPs mitigated cellular apoptosis and improved left ventricular function. Thus, delivery of S. elongatus encapsulated in HMPs improves clinical translation by utilizing a minimally invasive delivery platform that improves S. elongatus viability and enhances the therapeutic benefit of a novel photosynthetic system for the treatment of myocardial ischemia.

Hydrogel-Encapsulated Engineered Microbial Consortium as a Photoautotrophic "Living Material" for Promoting Skin Wound Healing

Genetically modified engineered microorganisms have been encapsulated in hydrogels and used as "living materials" for the treatment of skin diseases. However, their applications are often limited by the epidermal dry, nutrient-poor environment and cannot maintain functions stably for an expected sufficient time. To solve this problem, a photoautotrophic "living material" containing an engineered microbial consortium was designed and fabricated. The engineered microbial consortium comprised Synechococcus elongatus PCC7942 for producing sucrose by photosynthesis and another heterotrophic engineered bacterium (Escherichia coli or Lactococcus lactis) that can utilize sucrose for the growth and secretion of functional biomolecules. These engineered microorganisms in the "living material" were proved to function stably for a longer time than only individual microbes. Subsequently, CXCL12-secreting engineered L. lactis was used to construct the "living material", and its effect on promoting wound healing was verified in a full-thickness rat-skin defect model. The wounds treated by our hydrogel-encapsulated engineered microbial consortium (HeEMC) healed faster, with a wound area ratio of only 13.2% at day 14, compared to the remaining 62.6, 51.4, and 40.8% of the control, PEGDA, and PEGDA/CS groups, respectively. In conclusion, we established an efficient living material HeEMC to offer promising applications in the treatment of skin diseases.

Development of a photosynthetic hydrogel as potential wound dressing for the local delivery of oxygen and bioactive molecules

The development of biomaterials to improve wound healing is a critical clinical challenge and an active field of research. As it is well described that oxygen plays a critical role in almost each step of the wound healing process, in this work, an oxygen producing photosynthetic biomaterial was generated, characterized, and further modified to additionally release other bioactive molecules. Here, alginate hydrogels were loaded with the photosynthetic microalgae Chlamydomonas reinhardtii, showing high integration as well as immediate oxygen release upon illumination. Moreover, the photosynthetic hydrogel showed high biocompatibility in vitro and in vivo, and the capacity to sustain the metabolic oxygen requirements of zebrafish larvae and skin explants. In addition, the photosynthetic dressings were evaluated in 20 healthy human volunteers following the ISO-10993-10-2010 showing no skin irritation, mechanical stability of the dressings, and survival of the photosynthetic microalgae. Finally, hydrogels were also loaded with genetically engineered microalgae to release human VEGF, or pre-loaded with antibiotics, showing sustained release of both bioactive molecules. Overall, this work shows that photosynthetic hydrogels represent a feasible approach for the local delivery of oxygen and other bioactive molecules to promote wound healing. STATEMENT OF SIGNIFICANCE: As oxygen plays a key role in almost every step of the tissue regeneration process, the development of oxygen delivering therapies represents an active field of research, where photosynthetic biomaterials have risen as a promising approach for wound healing. Therefore, in this work a photosynthetic alginate hydrogel-based wound dressing containing C. reinhardtii microalgae was developed and validated in healthy skin of human volunteers. Moreover, hydrogels were modified to additionally release other bioactive molecules such as recombinant VEGF or antibiotics. The present study provides key scientific data to support the use of photosynthetic hydrogels as customizable dressings to promote wound healing.

Light-triggered photosynthetic engineered bacteria for enhanced-photodynamic therapy by relieving tumor hypoxic microenvironment

Background: Singlet oxygen (¹O₂) has received considerable research attention in photodynamic therapy (PDT) due to its cytotoxic solid features. However, the inherent hypoxic state of the tumor microenvironment (TME) leads to the meager ¹O₂ quantum yield of inorganic PDT reagents, and their application in vivo remains elusive. Methods: We developed a novel strategy to fabricate active photosynthetic bacteria/photosensitizer/photothermal agent hybrids for photosynthetic tumor oxygenation and PDT and PTT tumor therapy under different laser irradiation sources. Photosynthetic bacteria combined with Ce6 photosensitizer and Au NPs photothermal agent, the obtained Bac@Au-Ce6 effectively targets tumor tissues and further enhances the tumor accumulation of Au-Ce6. Results: The results showed that the Au-Ce6-loaded engineered bacteria (Bac@Au-Ce6) maintained the photosynthetic properties of Syne. After i.v. injection, Bac@Au-Ce6 efficiently aggregates at tumor sites due to the tumor-targeting ability of active Syne. With 660 nm laser irradiation at the tumor site, the photoautotrophic Syne undergoes sustained photosynthetic O₂ release and immediately activates O₂ to ¹O₂ via a loaded photosensitizer. PTT was subsequently imparted by 808 laser irradiations to enhance tumor killing further. Conclusions: This work provides a new platform for engineering bacteria-mediated photosynthesis to promote PDT combined with PTT multi-faceted anti-tumor.

The development of live microorganism-based oxygen shuttles for enhanced hypoxic tumor therapy

Hypoxia is a prominent feature of malignant tumors and contributes to tumor proliferation, metastasis, and drug resistance in various solid tumors. Therefore, improving tumor oxygenation is crucial for curing tumors. To date, multiple strategies, including oxygen delivering and producing materials, have been designed to increase the oxygen concentration in hypoxic tumors. However, the unsustainable supply of oxygen is still the main obstacle, resulting in a suboptimal outcome in treating oxygen-deprived tumors. Thus, a sufficient oxygen supply is highly desirable in the treatment of hypoxic tumors. Photosynthesis, as the main source of oxygen in nature through the conversion of light energy into chemical energy and oxygen, has been widely studied in scientific research. Moreover, photosynthetic microorganisms have been increasingly applied in cancer therapy by increasing oxygenation, which improves the therapeutic effect of oxygen-consuming tumor therapeutic tools such as radiotherapy and photodynamic therapy. In this review, we summarize recent advances in the design and manufacture of live bacteria as oxygen shuttles for a new generation of hypoxic tumor treatment strategies. Finally, current challenges and future directions are also discussed for successfully addressing hypoxic tumor issues.

Case report: Long-term follow-up of a large full-thickness skin defect treated with a photosynthetic scaffold for dermal regeneration

It is broadly described that almost every step of the regeneration process requires proper levels of oxygen supply; however, due to the vascular disruption in wounds, oxygen availability is reduced, being detrimental to the regeneration process. Therefore, the development of novel biomaterials combined with improved clinical procedures to promote wound oxygenation is an active field of research in regenerative medicine. This case report derives from a cohort of patients enrolled in a previously published ongoing phase I clinical trial (NCT03960164), to assess safety of photosynthetic scaffolds for the treatment of full skin defects. Here, we present a 56 year old patient, with a scar contracture in the cubital fossa, which impaired the elbow extension significantly affecting her quality of life. As part of the treatment, the scar contracture was removed, and the full-thickness wound generated was surgically covered with a photosynthetic scaffold for dermal regeneration, which was illuminated to promote local oxygen production. Then, in a second procedure, an autograft was implanted on top of the scaffold and the patient’s progress was followed for up to 17 months. Successful outcome of the whole procedure was measured as improvement in functionality, clinical appearance, and self-perception of the treated area. This case report underscores the long-term safety and applicability of photosynthetic scaffolds for dermal regeneration and their stable compatibility with other surgical procedures such as autograft application. Moreover, this report also shows the ability to further improve the clinical outcome of this procedure by means of dermal vacuum massage therapy and, more importantly, shows an overall long-term improvement in patient´s quality of life, supporting the translation of photosynthetic therapies into human patients.

Carbon-negative synthetic biology: challenges and emerging trends of cyanobacterial technology

Global warming and climate instability have spurred interest in using renewable carbon resources for the sustainable production of chemicals. Cyanobacteria are ideal cellular factories for carbon-negative production of chemicals owing to their great potentials for directly utilizing light and CO₂ as sole energy and carbon sources, respectively. However, several challenges in adapting cyanobacterial technology to industry, such as low productivity, poor tolerance, and product harvesting difficulty, remain. Synthetic biology may finally address these challenges. Here, we summarize recent advances in the production of value-added chemicals using cyanobacterial cell factories, particularly in carbon-negative synthetic biology and emerging trends in cyanobacterial applications. We also propose several perspectives on the future development of cyanobacterial technology for commercialization.

Towards an In Vitro 3D Model for Photosynthetic Cancer Treatment: A Study of Microalgae and Tumor Cell Interactions

As hypoxic tumors show resistance to several clinical treatments, photosynthetic microorganisms have been recently suggested as a promising safe alternative for oxygenating the tumor microenvironment. The relationship between organisms and the effect microalgae have on tumors is still largely unknown, evidencing the need for a simple yet representative model for studying photosynthetic tumor oxygenation in a reproducible manner. Here, we present a 3D photosynthetic tumor model composed of human melanoma cells and the microalgae Chlamydomonas reinhardtii, both seeded into a collagen scaffold, which allows for the simultaneous study of both cell types. This work focuses on the biocompatibility and cellular interactions of the two cell types, as well as the study of photosynthetic oxygenation of the tumor cells. It is shown that both cell types are biocompatible with one another at cell culture conditions and that a 10:1 ratio of microalgae to cells meets the metabolic requirement of the tumor cells, producing over twice the required amount of oxygen. This 3D tumor model provides an easy-to-use in vitro resource for analyzing the effects of photosynthetically produced oxygen on a tumor microenvironment, thus opening various potential research avenues.

Photoresponsive Hydrogel-Coated Upconversion Cyanobacteria Nanocapsules for Myocardial Infarction Prevention and Treatment

Myocardial infarction (MI) is a common disease that seriously threatens human health. It is noteworthy that oxygen is one of the key factors in the regulation of MI pathology procession: the controllable hypoxic microenvironment can enhance the tolerance of cardiac myocytes (CMs) and oxygen therapy regulates the immune microenvironment to repair the myocardial injury. Thus, the development of an oxygen-controllable treatment is critically important to unify MI prevention and timely treatment. Here, a hydrogel encapsulated upconversion cyanobacterium nanocapsule for both MI prevention and treatment is successfully synthesized. The engineered cyanobacteria can consume oxygen via respiration to generate a hypoxic microenvironment, resulting in the upregulation of heat shock protein70 (HSP70), which can enhance the tolerance of CMs for MI. When necessary, under 980 nm near-infrared (NIR) irradiation, the system releases photosynthetic oxygen through upconversion luminescence (UCL) to inhibit macrophage M1 polarization, and downregulates pro-inflammatory cytokines IL-6 and tumor necrosis factor-α (TNF-α), thereby repairing myocardial injury. To sum up, a photoresponsive upconversion cyanobacterium nanocapsule is developed, which can achieve MI prevention and treatment for only one injection via NIR-defined respiration and photosynthesis.

Engineering micro oxygen factories to slow tumour progression via hyperoxic microenvironments

While hypoxia promotes carcinogenesis, tumour aggressiveness, metastasis, and resistance to oncological treatments, the impacts of hyperoxia on tumours are rarely explored because providing a long-lasting oxygen supply in vivo is a major challenge. Herein, we construct micro oxygen factories, namely, photosynthesis microcapsules (PMCs), by encapsulation of acquired cyanobacteria and upconversion nanoparticles in alginate microcapsules. This system enables a long-lasting oxygen supply through the conversion of external radiation into red-wavelength emissions for photosynthesis in cyanobacteria. PMC treatment suppresses the NF-kB pathway, HIF-1α production and cancer cell proliferation. Hyperoxic microenvironment created by an in vivo PMC implant inhibits hepatocarcinoma growth and metastasis and has synergistic effects together with anti-PD-1 in breast cancer. The engineering oxygen factories offer potential for tumour biology studies in hyperoxic microenvironments and inspire the exploration of oncological treatments.

Microorganism-enabled photosynthetic oxygeneration and ferroptosis induction reshape tumor microenvironment for augmented nanodynamic therapy

Nanodynamic therapy (NDT) based on reactive oxygen species (ROS) generation has been envisioned as a distinct modality for efficient cancer treatment. However, insufficient ROS generation and partial ROS consumption frequently limit the theraputic effect and outcome of NDT owing to the low oxygen (O2) tension and high glutathione (GSH) level in tumor microenvironment (TME). To circumvent these critical issues, we herein proposed and engineered the biodegradable GSH-depletion Mn(III)-riched manganese oxide nanospikes (MnOx NSs) with the photosynthetic bacterial cyanobacteria (Cyan) as a high-efficient and synergistic platform to reshape TME by simultaneously increasing oxygen content and decreasing GSH level. Specifically, under the trigger of acidity, MnOx NSs reacted with photosynthetic oxygen can generate toxic singlet oxygen (1O2). Moreover, MnOx NSs significantly reduced intracellular GSH, resulting in decreased GPX4 activity, which induced tumor cell non-apoptotic ferroptosis. Consequently, this combined strategy based on coadministration with Cyan and MnOx NSs demonstrated the superior antitumor efficacy via amplification of oxidative stress in 4T1 tumor-bearing mice for the synergetic oxygen-augmented nanodynamic/ferroptosis therapy. This work highlights a facile synergistic micro-/nano-system with the specific capability of reshaping TME to augment the sensitivity and therapeutic efficacy of NDT in solid hypoxic tumor therapy.

How Microalgae is Effective in Oxygen Deficiency Aggravated Diseases? A Comprehensive Review of Literature

Hypoxia can aggravate the conditions of many oxygen-deficiency-aggravated diseases (ODAD), such as cancer, ischemic heart disease, and chronic wounds. Photosynthetic microalgae can alleviate the hepatotoxicity of the local microenvironment by producing oxygen. In addition, microalgae extracts have antitumor, anti-inflammatory, antibacterial, and antioxidant effects. These properties make them attractive candidates for developing methods to treat ODAD. Although researchers have exploited the advantages of microalgae and developed a variety of microalgae-based biomaterials to treat ODAD, a comprehensive review of this topic has not been presented previously. Therefore, in this review, we summarize the development and progress made in the field of developing microalgae-based biomaterials toward the treatment of ODAD. The challenges and prospects of this field are also discussed.

A novel photosynthetic biologic topical gel for enhanced localized hyperoxygenation augments wound healing in peripheral artery disease

Peripheral artery disease and the associated ischemic wounds are substantial causes of global morbidity and mortality, affecting over 200 million people worldwide. Although advancements have been made in preventive, pharmacologic, and surgical strategies to treat this disease, ischemic wounds, a consequence of end-stage peripheral artery disease, remain a significant clinical and economic challenge. Synechococcus elongatus is a cyanobacterium that grows photoautotrophically and converts carbon dioxide and water into oxygen. We present a novel topical biologic gel containing S. elongatus that provides oxygen via photosynthesis to augment wound healing by rescuing ischemic tissues caused by peripheral artery disease. By using light rather than blood as a source of energy, our novel topical therapy significantly accelerated wound healing in two rodent ischemic wound models. This novel topical gel can be directly translated to clinical practice by using a localized, portable light source without interfering with patients' daily activities, demonstrating potential to generate a paradigm shift in treating ischemic wounds from peripheral artery disease. Its novelty, low production cost, and ease of clinical translatability can potentially impact the clinical care for millions of patients suffering from peripheral arterial disease.

Engineering of optogenetic devices for biomedical applications in mammalian synthetic biology

Gene- and cell-based therapies are the next frontiers in the field of medicine. Both are transformative and innovative therapies; however, a lack of safety data limits the translation of such promising technologies to the clinic. Improving the safety and promoting the clinical translation of these therapies can be achieved by tightly regulating the release and delivery of therapeutic outputs. In recent years, the rapid development of optogenetic technology has provided opportunities to develop precision-controlled gene- and cell-based therapies, in which light is introduced to precisely and spatiotemporally manipulate the behaviour of genes and cells. This review focuses on the development of optogenetic tools and their applications in biomedicine, including photoactivated genome engineering and phototherapy for diabetes and tumours. The prospects and challenges of optogenetic tools for future clinical applications are also discussed.

Photosynthetic microorganisms for the oxygenation of advanced 3D bioprinted tissues

3D bioprinting technology has emerged as a tool that promises to revolutionize the biomedical field, including tissue engineering and regeneration. Despite major technological advancements, several challenges remain to be solved before 3D bioprinted tissues could be fully translated from the bench to the bedside. As oxygen plays a key role in aerobic metabolism, which allows energy production in the mitochondria; as a consequence, the lack of tissue oxygenation is one of the main limitations of current bioprinted tissues and organs. In order to improve tissue oxygenation, recent approaches have been established for a broad range of clinical applications, with some already applied using 3D bioprinting technologies. Among them, the incorporation of photosynthetic microorganisms, such as microalgae and cyanobacteria, is a promising approach that has been recently explored to generate chimerical plant-animal tissues where, upon light exposure, oxygen can be produced and released in a localized and controlled manner. This review will briefly summarize the state-of-the-art approaches to improve tissue oxygenation, as well as studies describing the use of photosynthetic microorganisms in 3D bioprinting technologies. STATEMENT OF SIGNIFICANCE: 3D bioprinting technology has emerged as a tool for the generation of viable and functional tissues for direct in vitro and in vivo applications, including disease modeling, drug discovery and regenerative medicine. Despite the latest advancements in this field, suboptimal oxygen delivery to cells before, during and after the bioprinting process limits their viability within 3D bioprinted tissues. This review article first highlights state-of-the-art approaches used to improve oxygen delivery in bioengineered tissues to overcome this challenge. Then, it focuses on the emerging roles played by photosynthetic organisms as novel biomaterials for bioink generation. Finally, it provides considerations around current challenges and novel potential opportunities for their use in bioinks, by comparing latest published studies using algae for 3D bioprinting.

Organismal and cellular interactions in vertebrate-alga symbioses

Photosymbioses, intimate interactions between photosynthetic algal symbionts and heterotrophic hosts, are well known in invertebrate and protist systems. Vertebrate animals are an exception where photosynthetic microorganisms are not often considered part of the normal vertebrate microbiome, with a few exceptions in amphibian eggs. Here, we review the breadth of vertebrate diversity and explore where algae have taken hold in vertebrate fur, on vertebrate surfaces, in vertebrate tissues, and within vertebrate cells. We find that algae have myriad partnerships with vertebrate animals, from fishes to mammals, and that those symbioses range from apparent mutualisms to commensalisms to parasitisms. The exception in vertebrates, compared with other groups of eukaryotes, is that intracellular mutualisms and commensalisms with algae or other microbes are notably rare. We currently have no clear cell-in-cell (endosymbiotic) examples of a trophic mutualism in any vertebrate, while there is a broad diversity of such interactions in invertebrate animals and protists. This functional divergence in vertebrate symbioses may be related to vertebrate physiology or a byproduct of our adaptive immune system. Overall, we see that diverse algae are part of the vertebrate microbiome, broadly, with numerous symbiotic interactions occurring across all vertebrate and many algal clades. These interactions are being studied for their ecological, organismal, and cellular implications. This synthesis of vertebrate-algal associations may prove useful for the development of novel therapeutics: pairing algae with medical devices, tissue cultures, and artificial ecto- and endosymbioses.

Far-Red Light Triggered Production of Bispecific T Cell Engagers (BiTEs) from Engineered Cells for Antitumor Application

Bispecific T-cell engagers (BiTEs), which have shown potent antitumor activity in humans, are emerging as one of the most promising immunotherapeutic strategies for cancer treatment in recent years. However, the clinical application of BiTEs nowadays has been hampered by their short half-life in the circulatory system due to their low molecular weight and rapid renal clearance. Inevitable continuous infusion of BiTEs has become a routine operation in order to achieve effective treatment, although it is costly, inconvenient, time-consuming, and even painful for patients in some cases. To develop an on-demand, tunable, and reversible approach to overcome these limitations, we assembled a transcription-control device into mammalian cells based on a bacterial far-red light (FRL) responsive signaling pathway to drive the expression of a BiTE against Glypican 3 (GPC3), which is a highly tumor-specific antigen expressed in most hepatocellular carcinomas (HCC). As demonstrated in in vitro experiments, we proved that the FRL sensitive device spatiotemporally responded to the control of FRL illumination and produced a therapeutic level of BiTEs that recruited and activated human T cells to eliminate GPC3 positive tumor cells. By functionally harnessing the power of optogenetics to remotely regulate the production of BiTEs from bioengineered cells and demonstrating its effectiveness in treating tumor cells, this study provides a novel approach to achieve an in vivo supply of BiTEs, which could be potentially applied to other formats of bispecific antibodies and facilitate their clinical applications.

Photosynthetic Oxygenation-Augmented Sonodynamic Nanotherapy of Hypoxic Tumors

Reactive oxygen species (ROS) has been employed as a powerful therapeutic agent for eradicating tumor via oxidative stress. As an emerging ROS-involving noninvasive anticancer therapeutic modality, sonodynamic therapy (SDT) with high tissue penetration depth and benign remote spatiotemporal selectivity has been progressively utilized as the distinct alternative for ROS-based tumor treatment. However, the hypoxic tumor microenvironment substantially restricts the sonodynamic effect. In this work, an oxygen self-sufficient hybrid sonosensitizer on the basis of photosynthetic microorganisms cyanobacteria (Cyan) integrated with ultrasmall oxygen-deficient bimetallic oxide Mn_1.4 WO_x nanosonosensitizers, termed as M@C, is designed and engineered to overcome the critical issue of hypoxia-induced tumor resistance and strengthen the SDT effect. The sustained photosynthetic oxygen production by Cyan under light illumination can promote Mn_1.4 WO_x nanosonosensitizers to produce more ROS against cancer cells both in vitro and in vivo under ultrasound (US) irradiation. Especially, the sustained oxygen evolution for suppressing the gene expression of hypoxia-inducible factor 1alpha (HIF-1α) further boosts and augments the SDT efficiency. Thus, this work provides the paradigm that the rationally engineered biohybrid microorganism-based multifunctional sonosensitizers can serve as an effective bioplatform for augmenting the therapeutic efficiency of SDT, particularly for the treatment of hypoxic tumors.

Development of a Novel Perfusable Solution for ex vivo Preservation: Towards Photosynthetic Oxygenation for Organ Transplantation

Oxygen is the key molecule for aerobic metabolism, but no animal cells can produce it, creating an extreme dependency on external supply. In contrast, microalgae are photosynthetic microorganisms, therefore, they are able to produce oxygen as plant cells do. As hypoxia is one of the main issues in organ transplantation, especially during preservation, the main goal of this work was to develop the first generation of perfusable photosynthetic solutions, exploring its feasibility for ex vivo organ preservation. Here, the microalgae Chlamydomonas reinhardtii was incorporated in a standard preservation solution, and key aspects such as alterations in cell size, oxygen production and survival were studied. Osmolarity and rheological features of the photosynthetic solution were comparable to human blood. In terms of functionality, the photosynthetic solution proved to be not harmful and to provide sufficient oxygen to support the metabolic requirement of zebrafish larvae and rat kidney slices. Thereafter, isolated porcine kidneys were perfused, and microalgae reached all renal vasculature, without inducing damage. After perfusion and flushing, no signs of tissue damage were detected, and recovered microalgae survived the process. Altogether, this work proposes the use of photosynthetic microorganisms as vascular oxygen factories to generate and deliver oxygen in isolated organs, representing a novel and promising strategy for organ preservation.

Algae on the brain in bioengineering

Özugur et al. recently pushed the boundaries of augmented physiology through artificial symbioses. They microinjected algal cultures into tadpole (Xenopus laevis) hearts. The resulting capillary-bound algae produced physiologically relevant levels of oxygen, which could rescue neuronal hypoxia. This work contributes to the growing field of artificial photosymbioses.

A First in Human Trial Implanting Microalgae Shows Safety of Photosynthetic Therapy for the Effective Treatment of Full Thickness Skin Wounds

Insufficient oxygen supply represents a relevant issue in several fields of human physiology and medicine. It has been suggested that the implantation of photosynthetic cells can provide oxygen to tissues in the absence of a vascular supply. This approach has been demonstrated to be successful in several in vitro and in vivo models; however, no data is available about their safety in human patients. Here, an early phase-1 clinical trial (ClinicalTrials.gov identifier: NCT03960164, https://clinicaltrials.gov/ct2/show/NCT03960164) is presented to evaluate the safety and feasibility of implanting photosynthetic scaffolds for dermal regeneration in eight patients with full-thickness skin wounds. Overall, this trial shows that the presence of the photosynthetic microalgae Chlamydomonas reinhardtii in the implanted scaffolds did not trigger any deleterious local or systemic immune responses in a 90 days follow-up, allowing full tissue regeneration in humans. The results presented here represent the first attempt to treat patients with photosynthetic cells, supporting the translation of photosynthetic therapies into clinics.

Clinical Trial Registration:www.clinicaltrials.gov/ct2/show/NCT03960164, identifier: NCT03960164.

Persistent luminescence phosphor as in-vivo light source for tumoral cyanobacterial photosynthetic oxygenation and photodynamic therapy

Tumor oxygenation level has been regarded as an attractive target to elevate the efficiency of photodynamic therapy (PDT). Cyanobacterial photosynthesis-mediated reversal of tumor hypoxia could enable an oxygen-boosted PDT, but is limited by scant penetration depth and efficiency of external light. Herein, aiming at the dual purposes of reducing biological toxicity induced by long-term light irradiation and alleviating hypoxia, we here introduce a novel-designed CaAl₂O₄:Eu,Nd blue persistent luminescence material (PLM) as the in vivo light source after pre-excited in vitro. The ingenious construction of blue-emitting PLM with “optical battery” characteristics activates cyanobacterial cells and verteporfin simultaneously, which performs the successive oxygen supply and singlet oxygen generation without the long-term external excitation, resulting in the modulated tumor hypoxic microenvironment and enhanced photodynamic tumor proliferation inhibition efficiency. Both in vitro cellular assessment and in vivo tumor evaluation results affirm the advantages of self-produced oxygen PDT system and evidence the notable antineoplastic outcome. This work develops an irradiation-free photosynthetic bacteria-based PDT platform for the optimization of both oxygen production capacity and light utilization efficiency in cancer treatment, which is expected to promote the clinical progress of microbial-based photonic therapy.

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Construction of CaAl₂O₄:Eu,Nd PLM to generate ¹O₂ without the aid of exogenous light excitation.

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Cyanobacteria with light-triggered oxygenation effect were employed for the normalization of tumor microenvironment.

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A distinct exogenous “irradiation-free” cyanobacteria-based PDT platform was rationally engineered.

Ischemic Microenvironment-Responsive Therapeutics for Cardiovascular Diseases

Cardiovascular diseases caused by ischemia are attracting considerable attention owing to its high morbidity and mortality worldwide. Although numerous agents with cardioprotective benefits have been identified, their clinical outcomes are hampered by their low bioavailability, poor drug solubility, and systemic adverse effects. Advances in nanoscience and nanotechnology provide a new opportunity to effectively deliver drugs for treating ischemia-related diseases. In particular, cardiac ischemia leads to a characteristic pathological environment called an ischemic microenvironment (IME), significantly different from typical cardiac regions. These remarkable differences between ischemic sites and normal tissues have inspired the development of stimuli-responsive systems for the targeted delivery of therapeutic drugs to damaged cardiomyocytes. Recently, many biomaterials with intelligent properties have been developed to enhance the therapeutic benefits of drugs for the treatment of myocardial ischemia. Strategies for stimuli-responsive drug delivery and release based on IME include reactive oxygen species, pH-, hypoxia-, matrix metalloproteinase-, and platelet-inspired targeting strategies. In this review, state-of-the-art IME-responsive biomaterials for the treatment of myocardial ischemia are summarized. Perspectives, limitations, and challenges are also discussed for the further development of innovative and effective approaches to treat ischemic diseases with high effectiveness and biocompatibility.

Photosynthetic symbiotic therapeutics - An innovative, effective treatment for ischemic cardiovascular diseases

Ischemic heart disease is a major cause of global morbidity and mortality, affecting over 15 million patients in the United States. Recent advances in research and innovation have greatly broadened clinicians' ability to treatment ischemic heart disease and associated heart failure using various preventive, pharmacologic, and surgical strategies. Specifically, innovative photosynthetic symbiotic systems using Synechococcus elongatus has gained significant attention. S. elongatus is a unicellular cyanobacterium that can carry out oxygenic photosynthesis. Photosynthetic therapies have been developed to rescue ischemic tissue by taking up tissue-derived carbon dioxide and in turn releasing oxygen for sustained aerobic metabolism during ischemia. In this article, we review the application of cyanobacteria, specifically S. elongatus, in the field of biotechnology, ischemic heart disease, and other clinical applications in ischemic diseases. We also address the motivation for innovation and current limitations in the field of S. elongatus photosynthetic therapeutics for ischemic cardiovascular disease.