Effects of systemically transplanted allogeneic bone marrow multipotent mesenchymal stromal cells on rats' recovery after experimental polytrauma

Neglected No More: Emerging Cellular Therapies in Traumatic Injury

Traumatic injuries are a leading cause of death and disability in both military and civilian populations. Given the complexity and diversity of traumatic injuries, novel and individualized treatment strategies are required to optimize outcomes. Cellular therapies have potential benefit for the treatment of acute or chronic injuries, and various cell-based pharmaceuticals are currently being tested in preclinical studies or in clinical trials. Cellular therapeutics may have the ability to complement existing therapies, especially in restoring organ function lost due to tissue disruption, prolonged hypoxia or inflammatory damage. In this article we highlight the current status and discuss future directions of cellular therapies for the treatment of traumatic injury. Both published research and ongoing clinical trials are discussed here.

Can IL-6 predict the development of fat embolism in polytrauma? A rabbit model pilot experimental study

BACKGROUND

There are few studies in the literature that correlates the level of IL-6 with fat embolism syndrome (FES). But there is no conclusive correlative evidence of its specific relation to the establishment of FES. Also it is a proven fact that polytrauma due to its associated multiple long bone fracture and/or associated shock can predispose an individual to FES. By hypothesizing that polytrauma induces Fat Embolism in the animal; it was considered worthwhile to study the association of IL-6 in polytrauma induced Fat Embolism (FE) and to compare it with induced FE by injecting fatty acids in rabbits.

MATERIALS AND METHODS

An animal study was conducted in 32 New Zealand white rabbits. The animals were divided into 3 groups: control, fat embolism and polytrauma group. We injected 6 ml of normal saline and 0.2 ml of linoleic acid in the control and fat embolism group respectively. In the polytauma group we created bilateral femur and tibial shaft factures which were stabilized with intramedullary K- wires. Blood was taken before and at 6, 12 and 24 h after the procedure to measure plasma IL-6 levels. The rabbits were euthanized at 24 h and lungs were removed and stained for fat globules.

RESULTS

All rabbits in the fat embolism group and around 72.22% rabbits in polytrauma group had fat embolism. The IL-6 levels were raised in all the groups reaching a peak at 6 h after procedure with a decline in the values at 12 h for polytrauma and fat embolism group. IL-6 in the control group was stationary after an initial raise at 6 h. There was no statistically significant difference seen among the groups (p value > 0.05) at 6 h.

CONCLUSION

IL-6 is not a specific marker to fat embolism per se or polytrauma who later develop complications like FES. Even though the recent literature says that IL-6 is an early marker of fat embolism, still the diagnosis of fat embolism syndrome is clinical only and can be supplemented by laboratory markers. None of the laboratory markers individually is good enough to predict the development of FES in an individual.

Mesenchymal stem cell transplantation in polytrauma: Evaluation of bone and liver healing response in an experimental rat model

PURPOSE

Trauma is the most common cause of death of young people in the world. As known, mesenchymal stem cells (MSCs) accelerate tissue regeneration mechanisms. In our study, we aimed to investigate the effects of MSCs transplantation on the healing of liver and bone tissue by considering trauma secondary inflammatory responses.

METHODS

56 adult Wistar-albino rats were divided into two groups: the polytrauma (liver and bone) (n = 28), and the liver trauma group (n = 28). At 36 h and 5th day after surgery, both rats with polytrauma and with isolated liver injury received either intravenous (IV) or intraperitoneal (IP) injections of MSCs (one million cells per kg body weight). Untreated groups received IV and IP saline injections. At day 21 after surgery, liver, tibia and fibula of the subjects were excised and evaluated for histopathologic and histomorphometric examination. Additionally, whole blood count (white blood cells, hemoglobin and platelets), C-reactive protein (CRP), glucose, alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin, blood gas, and trauma markers interleukin-1B (IL-1B), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF alpha) levels were investigated.

RESULTS

In general, MSC transplantations were well tolerated by the subjects. It was found that ALT, CRP, albumin were significantly lower in rats which received MSCs (p < 0.001). Inflammation of the liver and bone tissue in the MSC-injected rats were significantly lower than that of the untreated groups.

CONCLUSIONS

Herewith we have shown that MSC infusion in posttraumatic rats leads to less aggressive and more effective consequences on liver and bone tissue healing. Human MSC treatment for trauma is still in early stages of development; thus standard protocols, and patient inclusion criteria should be established beforehand clinical trials.

Mesenchymal Stem Cells after Polytrauma: Actor and Target

Mesenchymal stem cells (MSCs) are multipotent cells that are considered indispensable in regeneration processes after tissue trauma. MSCs are recruited to damaged areas via several chemoattractant pathways where they function as “actors” in the healing process by the secretion of manifold pro- and anti-inflammatory, antimicrobial, pro- and anticoagulatory, and trophic/angiogenic factors, but also by proliferation and differentiation into the required cells. On the other hand, MSCs represent “targets” during the pathophysiological conditions after severe trauma, when excessively generated inflammatory mediators, complement activation factors, and damage- and pathogen-associated molecular patterns challenge MSCs and alter their functionality. This in turn leads to complement opsonization, lysis, clearance by macrophages, and reduced migratory and regenerative abilities which culminate in impaired tissue repair. We summarize relevant cellular and signaling mechanisms and provide an up-to-date overview about promising future therapeutic MSC strategies in the context of severe tissue trauma.

Current Concepts in Orthopedic Management of Multiple Trauma

Multiple trauma patients frequently present challenging clinical scenarios with musculoskeletal injuries being the most common indications for surgical procedures in these patients. Despite our substantial knowledge, a universally approved objective definition for “multiple trauma” is yet to be delineated. Several controversial aspects of economics, pathophysiology, animal models, diagnosis, management and outcome of patients with multiple trauma have recently been explored and although some progress has been made, it seems that the available evidence is still inconclusive in some occasions. This manuscript revisits several current concepts of multiple trauma that have been the focus of recent investigation. We aim to provide the reader with an updated perspective based on the most recently published literature in the field of multiple trauma.

The quest for a universal definition of polytrauma: a trauma registry-based validation study

BACKGROUND

A pilot validation recommended defining polytrauma as patients with an Abbreviated Injury Scale (AIS) score greater than 2 in at least two Injury Severity Score (ISS) body regions (2 × AIS score > 2). This study aimed to validate this definition on larger data set. We hypothesized that patients defined by the 2 × AIS score > 2 cutoff have worse outcomes and use more resources than those without 2 × AIS score > 2 and that this would therefore be a better definition of polytrauma.

METHODS

Patients injured between 2009 and 2011, with complete documentation of AIS by New South Wales Trauma Registry and 16 years and older were selected. Age and sex were obtained in addition to outcomes of ISS, hospital length of stay (LOS), intensive care unit (ICU) admission, ICU LOS, and mortality. We compared demographic characteristics and outcomes between patients with ISS greater than 15 who did and did not meet the 2 × AIS score > 2 definition. We then undertook regression analyses (logistic regression for binary outcomes [ICU admission and death] and linear regression for hospital and ICU LOS) to compare outcomes for patients with and without 2 × AIS score > 2, adjusting for sex and age categories.

RESULTS

In the adjusted analyses, patients with 2 × AIS score > 2 had twice the odds of being admitted to the ICU compared with those without 2 × AIS score > 2 (odds ratio, 2.5; 95% confidence interval [CI], 2.2-2.8) and 1.7 times the odds of dying (95% CI, 1.4-2.0; p < 0.001 for both models). Patients with 2 × AIS score > 2 also had a mean difference of 1.5 days longer stay in the hospital compared with those without 2 × AIS score > 2 (95% CI, 1.4-1.7) and 1.6 days longer ICU stay (95% CI, 1.4-1.8; p < 0.001 for all models).

CONCLUSION

Patients with 2 × AIS score > 2 had higher mortality, more frequent ICU admissions, and longer hospital and ICU stay than those without 2 × AIS score > 2 and represents a superior definition to the definitions for polytrauma currently in use.

LEVEL OF EVIDENCE

Diagnostic test/ criteria, level III.

Crucial role of IL1beta and C3a in the in vitro-response of multipotent mesenchymal stromal cells to inflammatory mediators of polytrauma

Multipotent mesenchymal stromal cells (MSC) exert immune-modulatory effects and support tissue regeneration in various local trauma models. In case of a polytrauma, high amounts of danger-associated molecular patterns are released, leading to a systemic increase of inflammatory mediators. The influence of such a complex inflammatory microenvironment on human MSC is mainly unknown so far. Therefore, we investigated the effects of a defined serum-free polytrauma “cocktail” containing ILͳbeta, IL6, IL8 and the anaphylatoxins C3a and C5a, in concentrations corresponding to those measured in the blood of polytrauma patients, on human MSC in vitro. The polytrauma cocktail induced directed migration of MSC with C3a representing its major soluble chemoattractive agent. Furthermore, the polytrauma cocktail and IL1beta upregulated the expression of MMP1 indicating a potential role of IL1beta to enhance MSC migration in the tissue context. COX2, PTGES and TSG6 were also found to be upregulated upon stimulation with the polytrauma cocktail or IL1beta, but not through other single factors of the polytrauma cocktail in pathophysiologically relevant concentrations. An RNA expression array of 84 inflammation-related genes revealed that both the polytrauma cocktail and IL1beta induced C3, CSF1, TLR3 and various chemokines without major qualitative or quantitative differences. These results indicate that IL1beta is a crucial mediator of the polytrauma cocktail in terms of immune-modulation and MMP1 expression. Thus, upon encountering the primary sterile, inflammatory milieu of a polytrauma, endogenous or systemically transfused MSC might be able to migrate to sites of injury, secrete TSG6 and PGE2 and to influence macrophage biology as observed in local trauma models.