Efficacy of polymyxin B-immobilized fiber column direct hemoperfusion for non-endotoxin-associated severe septic shock

Polymyxin B Hemoperfusion in Pediatric Septic Shock: Single-Center Observational Case Series

OBJECTIVES

To evaluate the use of direct hemoperfusion with polymyxin B-immobilized fiber (PMX-DHP) as adjunctive therapy during pediatric patients with septic shock.

DESIGN

Prospective observational study.

SETTING

Nine-bed PICUs at university referral hospital.

PATIENTS

Children (30 d to 15 yr) with septic shock and Pediatric Logistic Organ Dysfunction (PELOD)-2 score greater than or equal to 10 or Pediatric Risk of Mortality (PRISM) 3 score greater than or equal to 15, who were also receiving at least one inotrope.

INTERVENTION

Patients received 2-4 hour treatment with PMX-DHP 20R column on 2 consecutive days.

MEASUREMENTS AND MAIN RESULTS

We enrolled six children aged 21-167 months old (median, 99-mo old), with a body weight of 10-50 kg (median, 28 kg). All six patients had both PELOD-2 greater than or equal to 10 and PRISM-3 greater than or equal to 15, required invasive mechanical ventilation, and received standard treatment for septic shock before enrollment. We observed significant improvement in PELOD-2 score from baseline to 72 hours after the start of PMX-DHP (mean [95% CI] from 14.3 [12.2-16.5] to 6.0 [0.3-11.7]; p = 0.006). The vasoactive inotropic score (VIS) and lactate concentration also significantly decreased from baseline to 72 hours (VIS, 60 mmol/L [25-95 mmol/L] to 4.0 mmol/L [44.1-12 mmol/L]; p = 0.003; lactate, 2.4 mmol/L [1.0-3.8 mmol/L] to 1.0 mmol/L [0.5-1.5 mmol/L]; p = 0.01). Five of six patients survived. There was no device-related adverse event in these patients.

CONCLUSIONS

In this case series of treatment with PMX-DHP as adjunctive therapy in children with refractory septic shock and high baseline severity, we have shown that patient recruitment is feasible. We have also found that clinical hemodynamic and severity of illness scores at 72 hours may be potential end points for testing in future randomized controlled trials.

PolyBall: A new adsorbent for the efficient removal of endotoxin from biopharmaceuticals

The presence of endotoxin, also known as lipopolysaccharides (LPS), as a side product appears to be a major drawback for the production of certain biomolecules that are essential for research, pharmaceutical, and industrial applications. In the biotechnology industry, gram-negative bacteria (e.g., Escherichia coli) are widely used to produce recombinant products such as proteins, plasmid DNAs and vaccines. These products are contaminated with LPS, which may cause side effects when administered to animals or humans. Purification of LPS often suffers from product loss. For this reason, special attention must be paid when purifying proteins aiming a product as free as possible of LPS with high product recovery. Although there are a number of methods for removing LPS, the question about how LPS removal can be carried out in an efficient and economical way is still one of the most intriguing issues and has no satisfactory solution yet. In this work, polymeric poly-ε-caprolactone (PCL) nanoparticles (NPs) (dP = 780 ± 285 nm) were synthesized at a relatively low cost and demonstrated to possess sufficient binding sites for LPS adsorption and removal with ~100% protein recovery. The PCL NPs removed greater than 90% LPS from protein solutions suspended in water using only one milligram (mg) of NPs, which was equivalent to ~1.5 × 106 endotoxin units (EU) per mg of particle. The LPS removal efficacy increased to a higher level (~100%) when phosphate buffered saline (PBS containing 137 mM NaCl) was used as a protein suspending medium in place of water, reflecting positive effects of increasing ionic strength on LPS binding interactions and adsorption. The results further showed that the PCL NPs not only achieved 100% LPS removal but also ~100% protein recovery for a wide concentration range from 20-1000 μg/ml of protein solutions. The NPs were highly effective in different buffers and pHs. To scale up the process further, PCL NPs were incorporated into a supporting cellulose membrane which promoted LPS adsorption further up to ~100% just by running the LPS-containing water through the membrane under gravity. Its adsorption capacity was 2.8 × 106 mg of PCL NPs, approximately 2 -fold higher than that of NPs alone. This is the first demonstration of endotoxin separation with high protein recovery using polymer NPs and the NP-based portable filters, which provide strong adsorptive interactions for LPS removal from protein solutions. Additional features of these NPs and membranes are biocompatible (environment friendly) recyclable after repeated elution and adsorption with no significant changes in LPS removal efficiencies. The results indicate that PCL NPs are an effective LPS adsorbent in powder and membrane forms, which have great potential to be employed in large-scale applications.