Evaluation of Mesenchymal Stem Cell Therapy for Sepsis: A Randomized Controlled Porcine Study

Abstract

Background: Treatment with mesenchymal stem cells (MSCs) has elicited considerable interest as an adjunctive therapy in sepsis. However, the encouraging effects of experiments with MSC in rodents have not been adequately studied in large-animal models with better relevance to human sepsis. Objectives: Here, we aimed to assess safety and efficacy of bone marrow-derived MSCs in a clinically relevant porcine model of progressive peritonitis-induced sepsis. Methods: Thirty-two anesthetized, mechanically ventilated, and instrumented pigs were randomly assigned into four groups (n = 8 per group): (1) sham-operated group (CONTROL); (2) sham-operated group treated with MSCs (MSC-CONTROL); (3) sepsis group with standard supportive care (SEPSIS); and (4) sepsis group treated with MSCs (MSC-SEPSIS). Peritoneal sepsis was induced by inoculating cultivated autologous feces. MSCs (1 × 10⁶/kg) were administered intravenously at 6 h after sepsis induction. Results: Before, 12, 18, and 24 h after the induction of peritonitis, we measured systemic, regional, and microvascular hemodynamics, multiple-organ functions, mitochondrial energy metabolism, systemic immune-inflammatory response, and oxidative stress. Administration of MSCs in the MSC-CONTROL group did not elicit any measurable acute effects. Treatment of septic animals with MSCs failed to mitigate sepsis-induced hemodynamic alterations or the gradual rise in Sepsis-related organ failure assessment scores. MSCs did not confer any protection against sepsis-mediated cellular myocardial depression and mitochondrial dysfunction. MSCs also failed to modulate the deregulated immune-inflammatory response. Conclusion: Intravenous administration of bone marrow-derived MSCs to healthy animals was well-tolerated. However, in this large-animal, clinically relevant peritonitis-induced sepsis model, MSCs were not capable of reversing any of the sepsis-induced disturbances in multiple biological, organ, and cellular systems.

Keywords: acute organ dysfunction; cell therapy; immunomodulation; mesenchymal stem cells; sepsis; septic shock.

Figure 1

Basic scheme of experimental protocol. The (*) stands for peritonitis induction in septic groups (SEPSIS and MSC-SEPSIS). The (**) stands for MSCs administration in treated groups (MSC-CONTROL and MSC-SEPSIS).

Figure 2

Particular subpopulations of leukocytes were gated from singlets populations followed by gating on FSC and SSC (A,C) and followed by gating on specific T regulatory (T reg) lymphocytes (A), on CD14+ CD16+ monocytes (B), and on T-helper (Th) lymphocytes and cytotoxic (Tc) + CD8α+ γδ T lymphocytes (C).

Figure 3

The quality of transplanted MSCs was monitored by expression of stem cell surface markers and by differentiation ability. MSCs were negative to CD45 and positive to CD90, CD73, and CD44 (A). They differentiate into adipo- (B), chondro- (C), and osteo- (D) lineage in 21 days of differentiation protocol.

Figure 4

(A) Cardiac output, systemic vascular resistance (B), total dose of norepinephrine (C) and total fluid balance (D). The (*) stands for significant difference in time (p < 0.05 vs. baseline).

Figure 5

Sepsis-related organ failure assessment (SOFA) score (A), Interleukin-6 (B), and TNFα serum levels (C). The (#) stands for statistical significance between the groups (p < 0.05). The (*) stands for significant differences in time in particular groups (p < 0.05 vs. baseline).

Figure 6

The absolute numbers of CD14/CD16^pos monocytes (A), T helper lymphocytes (B), Tc + CD8α+ γδ T lymphocytes (C), and T regulatory lymphocytes (D). The (*) stands for significant difference between particular time point and baseline only (p < 0.05).

Figure 7

Cellular myocardial depression. (A) Relative sarcomeric contraction amplitudes in cardiac myocytes from septic animals with or without application of MSC. (B) Mitochondrial respiration. Complex II-dependent oxygen consumption in septic myocardium without or with application of MSC. (C) Mitochondrial respiration. Complex IV-dependent oxygen consumption in septic myocardium without or with application of MSC.