Production and purification of urokinase: A comprehensive review

The Role of the Plasminogen/Plasmin System in Inflammation of the Oral Cavity

The oral cavity is a unique environment that consists of teeth surrounded by periodontal tissues, oral mucosae with minor salivary glands, and terminal parts of major salivary glands that open into the oral cavity. The cavity is constantly exposed to viral and microbial pathogens. Recent studies indicate that components of the plasminogen (Plg)/plasmin (Pm) system are expressed in tissues of the oral cavity, such as the salivary gland, and contribute to microbial infection and inflammation, such as periodontitis. The Plg/Pm system fulfills two major functions: (a) the destruction of fibrin deposits in the bloodstream or damaged tissues, a process called fibrinolysis, and (b) non-fibrinolytic actions that include the proteolytic modulation of proteins. One can observe both functions during inflammation. The virus that causes the coronavirus disease 2019 (COVID-19) exploits the fibrinolytic and non-fibrinolytic functions of the Plg/Pm system in the oral cavity. During COVID-19, well-established coagulopathy with the development of microthrombi requires constant activation of the fibrinolytic function. Furthermore, viral entry is modulated by receptors such as TMPRSS2, which is necessary in the oral cavity, leading to a derailed immune response that peaks in cytokine storm syndrome. This paper outlines the significance of the Plg/Pm system for infectious and inflammatory diseases that start in the oral cavity.

Safety and efficacy of low-cost alternative urokinase in acute ischemic stroke: A systematic review and meta-analysis

INTRODUCTION

Use of intravenous thrombolysis (IVT) for treatment of acute ischemic stroke (AIS) varies greatly between countries, ranging from 10% to 15% in high-income countries to less than 2% in low- and middle income countries (LMICs). This is because alteplase is expensive and has been cited as one of the most common barriers to IVT in LMICs. Urokinase (UK) is a thrombolytic agent which is almost 50 times cheaper with easier production and purification than alteplase. UK may become a cost-effective option for IVT in LMICs if it is found to be safe and effective. We conducted this study to assess the existing evidence on the safety and efficacy of UK vs alteplase for IVT in AIS.

METHODS

The study was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and meta-Analyses) guideline. Systematic literature search was done in PubMed, EMBASE, and Google Scholar for English literature published from 2010 to 2021.

RESULTS

A total of 4061 participants in the alteplase and 2062 participants in the UK group were included in the final statistical analysis. After IVT, a good functional outcome at last follow-up was found among 80.57 % of patients in the alteplase group compared to 73.79 % of patients in the UK group (OR: 1.11; 95 % CI: 0.95- 1.31; I2 = 0 %; P = 0.18). Symptomatic Intracerebral Hemorrhage (sICH) was found among 1.77 % of patients in the alteplase group compared to 2.83 % of patients in the UK group (OR: 0.84; 95 % CI: 0.56- 1.26; I2 = 0 %; P = 0.41). Similarly, mortality was found among 5.03 % of patients in the alteplase group compared to 5.42 % of patients in the UK group (OR: 0.87; 95 % CI: 0.66-1.14; I2 = 0 %; P = 0.30).

CONCLUSION

Our meta-analysis found that intravenous UK is not inferior to alteplase in terms of safety and efficacy and can be a viable alternative for IVT in AIS patients in LMICs.

Evolution of ischemic stroke drug clinical trials in mainland China from 2005 to 2021

Background

To assess the temporal changes in the characteristics of ischemic stroke drug clinical trials conducted in mainland China in 2005–2021.

Methods

A statistical analysis of registered clinical trials on ischemic stroke was performed using the platform of the Center for Drug Evaluation of China National Medical Products Administration, the Chinese Clinical Trial Registry, and ClinicalTrials.gov websites.

Results

From January 1, 2005 to August 1, 2021, a total of 384 registered drug clinical trials on ischemic stroke were identified in mainland China. Over time, the number of trials gradually increased each year, with a significant growth in 2014, from 16 in 2013 to 42 in 2014. Phase IV trials (31.8%) accounted for the majority, followed by phase II (16.4%), phase I (10.9%), and phase III (8.6%). In terms of sponsorship, the proportion of investigator‐initiated trials (IITs) (60.7%) was higher than industry‐sponsored trials (ISTs) (39.3%). Additionally, trials involving traditional Chinese medicines (TCMs) (36.2%) accounted for the largest proportion, followed by trials involving antithrombotic therapy (19.5%) and cerebral protection agents (16.7%). Furthermore, over the past 17 years, the number of leading drug clinical trial units for ischemic stroke in mainland China has continuously increased. The leading principal units from Beijing, Shanghai, Guangdong, Jiangsu, and Liaoning accounted for the majority of the trials (67.4%).

Conclusion

In the past 17 years, great progress has been made in the research and development (R&D) of drugs and clinical trials for ischemic stroke in mainland China. The most extensive progress was observed in TCMs, antithrombotic therapy, and cerebral protection agents. More clinical trials are needed to confirm whether the newly developed drugs can improve the clinical efficacy of ischemic stroke. Simultaneously, more pharmaceutical R&D efforts of innovative drugs are warranted.

Urokinase plasminogen activator as an anti-metastasis target: inhibitor design principles, recent amiloride derivatives, and issues with human/mouse species selectivity

The urokinase plasminogen activator (uPA) is a widely studied anticancer drug target with multiple classes of inhibitors reported to date. Many of these inhibitors contain amidine or guanidine groups, while others lacking these groups show improved oral bioavailability. Most of the X-ray co-crystal structures of small molecule uPA inhibitors show a key salt bridge with the side chain carboxylate of Asp189 in the S1 pocket of uPA. This review summarises the different classes of uPA inhibitors, their binding interactions and experimentally measured inhibitory potencies and highlights species selectivity issues with attention to recently described 6-substituted amiloride and 5‑N,N-(hexamethylene)amiloride (HMA) derivatives.

The evolution of recombinant thrombolytics: Current status and future directions

Cardiovascular disorders are on the rise worldwide due to alcohol abuse, obesity, hypertension, raised blood lipids, diabetes and age-related risks. The use of classical antiplatelet and anticoagulant therapies combined with surgical intervention helped to clear blood clots during the inceptive years. However, the discovery of streptokinase and urokinase ushered the way of using these enzymes as thrombolytic agents to degrade the fibrin network with an issue of systemic hemorrhage. The development of second generation plasminogen activators like anistreplase and tissue plasminogen activator partially controlled this problem. The third generation molecules, majorly t-PA variants, showed desirable properties of improved stability, safety and efficacy with enhanced fibrin specificity. Plasmin variants are produced as direct fibrinolytic agents as a futuristic approach with targeted delivery of these drugs using liposome technlogy. The novel molecules from microbial, plant and animal origin present the future of direct thrombolytics due to their safety and ease of administration.

Para-aminobenzamidine linked regenerated cellulose membranes for plasminogen activator purification: effect of spacer arm length and ligand density

Despite membrane-based separations offering superior alternative to packed bed chromatographic processes, there has been a substantial lacuna in their actual application to separation processes. One of the major reasons behind this is the lack of availability of appropriately modified or end-group modifiable membranes. In this paper, an affinity membrane was developed using a commercially available serine protease inhibitor, para-aminobenzamidine (pABA). The membrane modification was optimized for protein binding capacity by varying: (i) the length of the spacer arm (SA; 5-atoms, 7-atoms, and 14-atoms) linking the ligand to membrane surface; (ii) the affinity ligand (pABA) density on membrane surface (5-25nmol/cm(2)). Resulting membranes were tested for their ability to bind plasminogen activators (PAs) from mono- and multi-component systems in batch mode. The membrane containing pABA linked through 7-atoms SA but similar ligand density as in the case of 5- or 14-atoms long SA was found to bind up to 1.6-times higher amounts of PA per nmoles of immobilized ligand from conditioned HeLa cell culture media. However, membranes with similar ligand densities but different lengths of SA, showed comparable binding capacities in mono-component system. In addition, the length of SA did not affect the selectivity of the ligand for PA. A clear inverse linear correlation was observed between ligand density and binding capacity until the point of PA binding optima was reached (11±1.0nmol/cm(2)) in mono- and multi-component systems for 7- as well as 14-atoms SA. Up to 200-fold purification was achieved in a single step separation of PA from HeLa conditioned media using these affinity membranes. The issues of ligand leaching and reuse of the membranes were also investigated. An extensive regeneration procedure allowed the preservation of approximately 95% of the PA binding capacity of the membranes even after five cycles of use.

External modulation of HT-1080 human fibrosarcoma cells improves urokinase production

Urokinase was produced in a hollow fiber reactor using HT-1080 human fibrosarcoma cells. External modulation comprised replenishing of the medium in the extracapillary space, reducing the serum concentration in the extracapillary space from 10% to 2% and increasing flow rate of the circulating medium in the intracapillary space from 20 to 80 mL/min, each according to a specific protocol. More than sixfold increase was observed in the cumulative urokinase production for two and three medium replenishing modulations of the extracapillary space. After 15 days of continuous operation, the highest cumulative urokinase obtained was 1.63 x 10(6) PU/mL. SDS-PAGE and zymogram study established that the urokinase obtained was in the high molecular weight range of 54 kDa. The effect of external modulation on cumulative urokinase production was visualized as trajectories with respect to the ratio of lactic acid production rate (LPR) to the glucose uptake rate (GUR). The collective external modulation data showed two separate physiological regions in the cumulative urokinase vs. LPR/GUR plane. The HT-1080 cells exhibited two distinct morphologies in these regions that may be related to acidosis and metastasis. These regions also correspond to low and high urokinase productivity.

Recovery of urokinase from integrated mammalian cell culture cryogel bioreactor and purification of the enzyme using p-aminobenzamidine affinity chromatography

An integrated product recovery system was developed to separate urokinase from the cell culture broth of human kidney cells HT1080. Supermacroporous monolithic cryogels provided ideal matrices with respect to surface and flow properties for use as cell culture scaffold as well as for affinity chromatographic capture step of the enzyme in the integrated system. The urokinase was produced continuously in the reactor running for 4 weeks with continuous circulation of 500 ml of culture medium. The enzyme activity in the culture medium reached to 280 Plough units (PU)/mg protein. Cu(II)-iminodiacetic acid (IDA)-polyacrylamide (pAAm) cryogel column was used to capture urokinase by integrating with the gelatin-coupled pAAm-cryogel bioreactor for HT1080 cell culture. After removing the urokinase capture column from the integrated system the bound protein was eluted. The metal affinity capture step gave 4.5-fold purification of the enzyme thus achieving a specific activity of 1300 PU/mg protein. The enzyme eluate from Cu(II)-IDA-pAAm cryogel capture column was further purified on benzamidine-Sepharose affinity column. This step finally led to a homogeneous preparation of different forms of urokinase in two different elution peaks with a best urokinase activity of 13 550 PU/mg of protein. As compared to initial activity in the cell culture broth, about 26.2- and 48.4-fold increase in specific activity was achieved with enzyme yields corresponding to 32% and 35% in two different peak fractions, respectively. Native electrophoresis and SDS-PAGE showed multiple protein bands corresponding to different forms of the urokinase, which were confirmed by Western blotting and zymography.

Synthesis, regulation and production of urokinase using mammalian cell culture: a comprehensive review

Urokinase, a serine protease, catalyzes the conversion of plasminogen to plasmin, which is responsible for dissolution of clots in blood vessels. It is an important drug for treatment of thromboembolic disease. Production of urokinase by mammalian cell culture has the following important steps: synthesis, regulation and secretion. Production and accumulation of this product in a bioreactor is a real challenge for biochemical engineers. Considerable information at molecular level needs to be understood for production of urokinase in order to correlate different parameters, which in turn can maximize the productivity. This information will be highlighted in this review. Moreover, urokinase production is a product-inhibited process. Therefore, in situ urokinase separation strategy is required to operate a bioreactor at its maximum urokinase formation rate. Integrated urokinase production and isolation processes developed recently will also be discussed briefly in this review.