Role of Stem Cells in Sepsis

Abstract

Sepsis is defined as the presence of infection together with systemic manifestations of infection. Severe sepsis is defined as sepsis plus sepsis-induced organ dysfunction or tissue hypoperfusion. Sepsis is characterized by • Fever (> 38.3°C). • Hypothermia (core temperature < 36°C). • Heart rate > 90/min–1 or more than two degree above the normal value for age. • Tachypnea. • Altered mental status. • Significant edema. • Hyperglycemia (plasma glucose > 140mg/dL or 7.7mmol/L) in the absence of diabetes. A stem cell is a cell that has the ability to divide asymmetrically to produce another cell like itself, or a more differentiated cell. In a developing embryo, stem cells can differentiate into all the specialized cells (these are called pluripotent cells), but also maintain the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues. There are three accessible sources of autologous adult stem cells in humans:  Bone marrow it requires extraction by harvesting, that is drilling into bone (typically the femur or iliac crest).  Adipose tissue (lipid cells) it requires extraction by liposuction  Blood it requires extraction through pheresis, where in blood is drawn from the donor (similar to a blood donation), passed through a machine that extracts the stem cells and returns other portions of the blood to the donor. Stem cells can also be taken from umbilical cord blood just after birth. Of all stem cell types, autologous harvesting involves the least risk. By definition, autologous cells are obtained from one's own body, just as one may bank his or her own blood for elective surgical procedures. Highly adult stem cells are routinely used in medical therapies, for example in bone marrow transplantation. Stem cells can now be artificially grown and transformed (differentiated) into specialized cell types with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture. Embryonic cell lines and autologous embryonic stem cells generated through therapeutic cloning have also been proposed as promising candidates for future therapies. Despite the state-of-the-art treatment strategies and advanced antibiotic regimens, acute sepsis syndrome, a global problem, remains the leading cause of death in hospitalized patients with infectious disease. Death from sepsis syndrome is caused by a complication process with the involvement of divergent factors. Of these factors, overwhelming immune response and inflammatory reaction are major contributors to direct or indirect assaults on the vital organs In addition, studies have shown that sepsis syndrome-related acute lung injury (ALI) and acute kidney injury (AKI) are commonly encountered in critically ill patients, Poor prognostic outcomes have been reported for patients in these clinical settings. The control of the overwhelming immune response and vigorous inflammatory reaction that contribute to the damage of lung and kidney, two vital and vulnerable organs, may be crucial in reducing sepsis-induced morbidity and mortality. Not only has growing evidence demonstrated that stem cells possess the intrinsic capacity of immunomodulation, but stem cell therapy has also been shown to attenuate inflammation and immune responses, and augment wound healing cells to favor tissue regeneration and inhibit fibrotic tissue formation.