How Synthetic Biology and Metabolic Engineering Can Boost the Generation of Artificial Blood Using Microbial Production Hosts

Abstract

Hemoglobin is an essential protein to the human body as it transports oxygen to organs and tissues through the bloodstream (Looker et al., 1992). In recent years, there has been an increasing concern regarding the global supply of this vital protein, as blood availability cannot currently meet the high demands in many developing countries. There are, in addition, several risks associated with conventional blood transfusions such as the presence of blood-borne viruses like HIV and Hepatitis. These risks along with some limitations are presented in Figure 1 (Kim and Greenburg, 2013; Martínez et al., 2015). As an alternative, producing hemoglobin recombinantly will eliminate the obstacles, since hemoglobin-based oxygen carriers are pathogen-free, have a longer shelf-life, are universally compatible and the supply can be adjusted to meet the demands (Chakane, 2017). A stable, safe, and most importantly affordable production, will lead to high availability of blood to the world population, and hence reduce global inequality, which is a focus point of the World Health Organization for the millennium (WHO, 2018). Synthetic biology and metabolic engineering have created a unique opportunity to construct promising candidates for hemoglobin production (Liu et al., 2014; Martínez et al., 2016). This review sets out to describe the recent advances in recombinant hemoglobin production, the societal and the economic impact along with the challenges that researchers will face in the coming years, such as low productivity, degradation, and difficulties in scale-up. The challenges are diverse and complex but with the powerful tools provided by synthetic biology and metabolic engineering, they are no longer insurmountable. An efficient production of cell-free recombinant hemoglobin poses tremendous challenges while having even greater potential, therefore some possible future directions are suggested in this review.

Precision Fermentation as an Alternative to Animal Protein, a Review

“…Hemoglobins have been adopted as acellular oxygen transporters, iron supplying agents and coloring and flavoring agents in the food industry. The use of recombinant human hemoglobin as an oxygen carrier in the production of artificial blood, for example, has been an alternative explored to meet the demand for blood transfusions worldwide [172][173][174]. Myoglobin is an important contributor to the sensory quality of meat, related to the red tone and metallic flavor.…”

Hemoglobin-Based Oxygen Carriers: Where Are We Now in 2023?

“…The first-in-human phase I clinical trial from 2020 to assess HbV’s safety and pharmacokinetics in healthy male adult volunteers found that HbV is safe and efficacious. HbV can potentially be used as an alternative to allogeneic blood transfusion as well as for oxygen and carbon monoxide therapy, perfusate for transplant organs, and photosensitizer [ 15 , 28 , 29 ]. Permission for a Phase I clinical trial was also granted to Dr. Sakai’s group in Japan [ 28 ].…”

“…The World Health Organization believes that synthetic biology and the development of engineering techniques have provided unique opportunities for global scientists to make promising hemoglobin production [ 29 ]. The various diverse and complex challenges, believed to be insurmountable, will be overcome with new developments in powerful synthetic biomedical and genetic engineering technologies [ 29 ].…”

How Nitric Oxide Hindered the Search for Hemoglobin-Based Oxygen Carriers as Human Blood Substitutes

“…The availability of site-directed mutagenesis techniques has enabled the production of recombinant human Hb variants targeted at specific functions. Today, engineered Saccharomyces cerevisiae or Corynebacterium glutamicum strains can produce up to 18-20% of total cell proteins as human Hb [154,155] at reasonable costs and high yields: a single 100 m 3 tank may produce 200 kg of Hb, i.e., the equivalent of 1300 L of blood [156]. Observing the characteristics of naturally occurring human Hb mutations provides lessons on how to design recombinant Hb [157].…”