Tunable Sulfated Alginate-based Hydrogel Platform with enhanced anti-inflammatory and antioxidant capacity for promoting burn wound repair.

Amidst progressive advancements in tissue engineering, there has been a significant enhancement in the efficacy of anti-inflammatory hydrogel dressings, addressing a myriad of clinical challenges on wound healing. A frequent complication during the initial stages of deep second-degree burn wound healing is the onset of an inflammatory storm, typically occurring without effective intervention. This event disrupts normal biological healing sequences, leading to undesirable regression. In response, we have customized a tunable, multidimensional anti-inflammatory hydrogel platform based on sulfated alginates (Algs), loaded with Prussian blue (PB) nanozymes. This platform competently eliminates surplus reactive oxygen species (ROS) present in the wound bed. Algs, functioning as a mimic of sulfated glycosaminoglycans (including heparin, heparan sulfate, and chondroitin sulfate) in the extracellular matrices (ECM), demonstrate a high affinity towards inflammatory chemokines such as interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1). This affinity effectively impedes the infiltration of inflammatory cells into the wound. Concurrently, Algs markedly modulate the macrophage phenotype transition from M1 to M2. Ultimately, our potent anti-inflammatory hydrogels, which strategically target inflammatory chemokines, M1 macrophages, and ROS, successfully attenuate dysregulated hyperinflammation in wound sites. Precise immunomodulation administered to deep second-degree burn wounds in mice has demonstrated promotion of neovascular maturation, granulation tissue formation, collagen deposition, and wound closure. Our biomimetic hydrogels, therefore, represent a significant expansion in the repertoire of anti-inflammatory strategies available for clinical practice.

Anti-inflammatory hydrogel dressings and skin wound healing.

Hydrogels are promising and widely utilized in the biomedical field. In recent years, the anti-inflammatory function of hydrogel dressings has been significantly improved, addressing many clinical challenges presented in ongoing endeavours to promote wound healing. Wound healing is a cascaded and highly complex process, especially in chronic wounds, such as diabetic and severe burn wounds, in which adverse endogenous or exogenous factors can interfere with inflammatory regulation, leading to the disruption of the healing process. Although insufficient wound inflammation is uncommon, excessive inflammatory infiltration is an almost universal feature of chronic wounds, which impedes a histological repair of the wound in a predictable biological step and chronological order. Therefore, resolving excessive inflammation in wound healing is essential. In the past 5 years, extensive research has been conducted on hydrogel dressings to address excessive inflammation in wound healing, specifically by efficiently scavenging excessive free radicals, sequestering chemokines and promoting M1 -to-M2 polarization of macrophages, thereby regulating inflammation and promoting wound healing. In this study, we introduced novel anti-inflammatory hydrogel dressings and demonstrated innovative methods for their preparation and application to achieve enhanced healing. In addition, we summarize the most important properties required for wound healing and discuss our analysis of potential challenges yet to be addressed.

Case Report: Tachycardia, Hypoxemia and Shock in a Severely Burned Pediatric Patient.

Background: Severely burned children are at high risk of secondary intraabdominal hypertension and abdominal compartment syndrome (ACS). ACS is a life-threatening condition with high mortality and requires an effective, minimally invasive treatment to improve the prognosis when the condition is refractory to conventional therapy. Case presentation: A 4.5-year-old girl was admitted to our hospital 30 h after a severe burn injury. Her symptoms of burn shock were relieved after fluid resuscitation. However, her bloating was aggravated, and ACS developed on Day 5, manifesting as tachycardia, hypoxemia, shock, and oliguria. Invasive mechanical ventilation, vasopressors, and percutaneous catheter drainage were applied in addition to medical treatments (such as gastrointestinal decompression, diuresis, sedation, and neuromuscular blockade). These treatments did not improve the patient's condition until she received continuous renal replacement therapy. Subsequently, her vital signs and laboratory data improved, which were accompanied by decreased intra-abdominal pressure, and she was discharged after nutrition support, antibiotic therapy, and skin grafting. Conclusion: ACS can occur in severely burned children, leading to rapid deterioration of cardiopulmonary function. Patients who fail to respond to conventional medical management should be considered for continuous renal replacement therapy.

[An improved technique for repairing hand defects with abdominal pedicled flaps].

OBJECTIVE: To explore the feasibility a modified method for repairing hand soft tissue defects using abdominal pedicle flaps. METHODS: Between January 1997 and October 2010, abdominal pedicle flaps were used to repair hand soft tissue defects in 108 cases. A strategy of segmented skin-flap ligations was adopted for early pedicle cut-off with early separation of the combined fingers, donor site closure with auxiliary flaps and application of thin flap and full-thickness skin graft. RESULTS: Ligation of the pedicle site only was performed in 68 cases with an average time of pedicle cut-off of 10 days. Pedicle cut-off and separation of the combined fingers were simultaneously performed in 40 cases without flap necrosis. The healing rate of the donor sites reached 96.8%. CONCLUSION: The method is simple, safe and reliable and allows simultaneous pedicle cut-off and separation of the combined fingers to ensure good functional and appearance recovery of the hand with soft tissue defect.

[Experimental study and clinical application of early pedicle division of skin flap by ligation].

OBJECTIVE: To establish a new method of early cut-off skin flap by ligating to stegnosis pedicle and assess its feasibility and clinical application. METHODS: Twenty New Zealand rabbits were used to make skin flaps with the size of 8.0 cm x 4.0 cm on both sides of the back respectively. And one side was experimental group with the pedicles of skin flaps horizontally oversewn by several pairs of silk thread, the other side was control group. Two pairs of silk thread in the two sides of the pedicle of skin flap of experimental group were ligated on the 3rd day. On the 5th day the pedicle was wholly ligated. All pedicles were divided on the 6th day and the survival area of skin flaps were measured after 3 days. The tissue samples from the skin flaps were collected for histology test on the 4th and 6th day respectively. The pedicles of 78 random flaps from 48 patients were cut off after narrowing them by ligating. RESULTS: The mean flap survival rate of the experimental group was statistically higher than the control group. Histological examination results showed the density and diameter of blood vessel were increased in the skin flaps of the experimental group. The mean time for removal pedicles was shortened to 10 days, and no necrosis was found after resecting. CONCLUSIONS: This method is secure and convenient and the time of pedicle division can be shortened.

[The use of local flap in repairing deeply burned wound of extremities].

OBJECTIVE: To discuss a method for reconstruction of deeply burned of extremities' functional regions with local skin flaps. METHODS: Ninety-eight cases (with 126 place) of deeply burned wound of extremities were reconstructed with fasciocutaneous flaps. RESULTS: The survival rate of 162 flaps was 93.2%. The movement of 112 joints (88.9%) was restored to normal, and the movement of 14 joints was mild limitation, none of the cases was severe obstacle. CONCLUSIONS: The method is simple and with satisfactory results, which can decrease the rate of disability suffered from burn.

[Investigation of a retrograded supra-genicular flap for treatment of scarring contraction of popiteal fossa].

OBJECTIVE: To investigate the blood vascular distribution of supra-genicular flap and to apply the retrograded supra-genicular flap for reconstructive surgery. METHODS: Eight fresh adult cadavers with 16 lower extremities were used for the study, by means of injecting the media of red latex into the main artery of the limb. The skin vascular architecture on the lower two thirds of each thigh was observed to decide the blood supply of this region. Fifty-two patients were also used to treat the scarring contraction of the popiteal fossa with 56 of the retrograded supra-genicular flaps, and long-term follow-ups were carried out. RESULTS: From this study, it was found that there are rich blood vascular networks of the skin above the knee anteriorally, laterally and medially. The abundant vascular anastomoses were also found around the knee. The clinical application of the retrograded supra-genicular flap was successfully carried out for the treatment of the scarring contraction of the popiteal fossa. All of the flaps were survived well. Long-term results were satisfactory. CONCLUSION: The above mentioned flap is a safe and effective flap for repair the defect of the popiteal fossa.