The extent of thermal injury affects fractions of mononuclear cells

Determination of lymphocytes surface markers in patients with thermal burns and the influence of burn size on mononuclear cell subsets

Background: Thermal burn injuries impair the host defence system. Hence, in the present study, we aimed at investigating the changes in the number and phenotype of peripheral blood lymphocyte populations (T, B, and natural killer cells) and their subpopulations in patients with thermal burns and determining the relationships with different sizes of total body surface area (TBSA). Methods: Blood samples from 67 patients, admitted to Motahary Burn Center in Tehran, with burns from 30% to more than 70% TBSA were collected on Days 3 and 7 postburn. Lymphocytes and their subpopulations were identified by monoclonal antibodies. The cells were analyzed using flow cytometry. The results were compared with healthy controls. Results: In this study, 3 and 7 days after burn injury, the percentages of CD3+, CD4+ and CD8+ lymphocyte significantly decreased, CD4+/CD8+ ratios were below the normal range, and CD19+ (B cells) significantly increased. No significant difference was obtained in the mean percentage of CD16+ (NK cells) between Days 3 and 7 postburn. Patients with burns of 30% TBSA or greater (>70%) had a significant reduction in CD3+, CD4+ and CD8+ ( T cells) numbers up to 7 days compared with 3 days after burn injury. Patients with 30% to >70 % TBSA burn failed to show any significant changes in CD4+/CD8+ ratio as well as CD16+ (NK cells) 3 to 7 days after burn. In patients with burns more than 30% to>70% TBSA, CD19+ (B cells) number changes were found to be complicated after 3 and 7 days. Conclusion: The results of this study suggest that alterations of immune cell surface markers and TBSA% can reflect postburn lymphocyte activation.

Endothelial progenitor cells and burn injury - exploring the relationship

Burn wounds result in varying degrees of soft tissue damage that are typically graded clinically. Recently a key participant in neovascularization, the endothelial progenitor cell, has been the subject of intense cardiovascular research to explore whether it can serve as a biomarker for vascular injury. In this review, we examine the identity of the endothelial progenitor cell as well as the evidence that support its role as a key responder after burn insult. While there is conflicting evidence with regards to the delta of endothelial progenitor cell mobilization and burn severity, it is clear that they play an important role in wound healing. Systematic and controlled studies are needed to clarify this relationship, and whether this population can serve as a biomarker for burn severity.

Endothelial progenitor cells--potential new avenues to improve neoangiogenesis and reendothelialization

The term endothelial progenitor cell (EPC) was established more than 10 years ago and is used to refer to a group of circulating cells that display endothelial lineage qualities and are able to home to areas of ischemia or vascular injury and to facilitate the repair of damaged blood vessels or develop new vessels as needed. This chapter reviews the current lineage relationships among all the cells called EPC and will clear the terminology used in EPC research. Furthermore, an overview of the clinical and in vitro research, as well as cytokine and drug interactions and potential EPC applications, is given.

An update review of stem cell applications in burns and wound care

The ultimate goal of the treatment of cutaneous burns and wounds is to restore the damaged skin both structurally and functionally to its original state. Recent research advances have shown the great potential of stem cells in improving the rate and quality of wound healing and regenerating the skin and its appendages. Stem cell-based therapeutic strategies offer new prospects in the medical technology for burns and wounds care. This review seeks to give an updated overview of the applications of stem cell therapy in burns and wound management since our previous review of the “stem cell strategies in burns care”.

Soluble CD163: A novel biomarker for the susceptibility to sepsis in severe burn injuries

Objective:

Soluble CD163 (sCD163) has been previously shown to play a role in inflammatory and infectious diseases. This study, for the first time, investigates the characteristics and potential values of sCD163 in burn patients. A first look is taken on the changes of sCD163 levels in burn patients by comparing predefined subgroups at single time points.

Materials and Methods:

Serum samples of 18 patients with burn injuries were collected for biochemical analysis at the time of admission and in a chronological sequence of 12, 24, 48 and 120 h after the injury and were matched to clinical parameters. Statistical analysis was performed using the Mann-Whitney test, Wilcoxon signed rank and Pearson bivariate correlation.

Results:

Patients with sepsis showed a significant increase of sCD163 levels. sCD163 was correlated with leukocytes (P=0.035) over the time course of 120 h. Patients characterized by a burn size exceeding 25% of the total body surface area (TBSA) showed a significant increase of sCD163 between 12 and 48 h after burn injury (P=0.038).

Conclusions:

The first view on the characteristics of sCD163 in the serum of burn patients points out that sCD163 seems to be an early indicator for the susceptibility to sepsis. Furthermore, the changes in sCD163 serum levels within the first hours after burn trauma have great potential for early prediction of organ failure after burn injury.

Blood levels, apoptosis, and homing of the endothelial progenitor cells after skin burns and escharectomy

BACKGROUND

Skin burns are an acute trauma involving an extensive vascular damage and an intense inflammatory response. Bone marrow-derived circulating endothelial progenitor cells (EPC) are known to migrate to sites of neovascularization in response to mediators (vascular endothelial growth factor and stromal cell-derived factor-1) released after trauma and ischemia, to contribute to wound healing, and to increase neovascularization of animal prefabricated flaps. Recent data showed an increase in EPC number in burned patients and a positive correlation between EPC number and total body surface area (TBSA) burnt, but data were limited to the first 5 days after thermal injury.

METHODS

By using flow cytometry, we studied EPC (CD34, CD133, CD45, and KDR cells) blood levels, apoptosis, and homing (stromal cell-derived factor-1 receptor expression and CXC chemokine receptor 4) in a 1-month follow-up postburn in 25 patients with ≥15% TBSA burnt, at least grade II burns and escharectomy performed at days 5 to 6, with respect to 31 controls.

RESULTS

EPC count at admission showed a positive linear correlation with TBSA burnt. The EPC blood levels of the patients were low (50.7 cells/mL±61.8 cells/mL) immediately after thermal injury, then increased with two peaks, at day 1 (188.3 cells/mL±223.2 cells/mL) and day 12 (253.1 cells/mL±430.7 cells/mL) with respect to controls (95.2 cells/mL±28.5 cells/mL, p<0.05), and then returned to normal levels in 1 month. EPC apoptotic rate and inflammatory parameters paralleled EPC blood count. No significant variations were found in CXC chemokine receptor 4 expression.

CONCLUSIONS

Thermal injury and escharectomy seem to induce an intense response in EPC production. In particular, escharectomy could improve physiologic wound repair by increasing EPC levels.

Human CD34+/KDR+ cells are generated from circulating CD34+ cells after immobilization on activated platelets

OBJECTIVE

The presence of kinase-insert domain-containing receptor (KDR) on circulating CD34+ cells is assumed to be indicative for the potential of these cells to support vascular maintenance and repair. However, in bone marrow and in granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood, less than 0.5% of CD34+ cells co-express KDR. Therefore, we studied whether CD34+/KDR+ cells are generated in the peripheral circulation.

METHODS AND RESULTS

Using an ex vivo flow model, we show that activated platelets enable CD34+ cells to home to sites of vascular injury and that upon immobilization, KDR is translocated from an endosomal compartment to the cell-surface within 15 minutes. In patients with diabetes mellitus type 2, the percentage of circulating CD34+ co-expressing KDR was significantly elevated compared to age-matched controls. When treated with aspirin, the patients showed a 49% reduction in the generation of CD34+/KDR+ cells, indicating that the level of circulating CD34+/KDR+ cells also relates to in vivo platelet activation.

CONCLUSIONS

Circulating CD34+/KDR+ are not mobilized from bone marrow as a predestined endothelial progenitor cell population but are mostly generated from circulating multipotent CD34+ cells at sites of vascular injury. Therefore, the number of circulating CD34+/KDR+ cells may serve as a marker for vascular injury.

Exploring the role of stem cells in cutaneous wound healing

The skin offers a perfect model system for studying the wound healing cascade, which involves a finely tuned interplay between several cell types, pathways and processes. The dysregulation of these factors may lead to wound healing disorders resulting in chronic wounds, as well as abnormal scars such as hypertrophic and keloid scars. As the contribution of stem cells towards tissue regeneration and wound healing is increasingly appreciated, a rising number of stem cell therapies for cutaneous wounds are currently under development, encouraged by emerging preliminary findings in both animal models and human studies. However, we still lack an in-depth understanding of the underlying mechanisms through which stem cells contribute to cutaneous wound healing. The aim of this review is, therefore, to present a critical synthesis of our current understanding of the role of stem cells in normal cutaneous wound healing. In addition to summarizing wound healing principles and related key molecular and cellular players, we discuss the potential participation of different cutaneous stem cell populations in wound healing, and list corresponding stem cells markers. In summary, this review delineates current strategies, future applications, and limitations of stem cell-based or stem cell-targeted therapy in the management of acute and chronic skin wounds.