In most emergency situations of uncontrolled hemorrhaging caused by tissue trauma, such as arterial rupture, visceral perforation and limb loss, lack of timely intervention may contribute to mass fatalities¹. Developing an ideal hemostat, which can rapidly seal wounds and allow for physical compression, is an effective hemostatic practice^2,3. Although many experimental hemostatic materials, such as chitosan, cellulose, and sodium alginate, have been tested and commercialized for rapid wound closure, they still present limitations². Even the most effective hemostatic agents present limitations such as potential toxicity of the derivatives, slow wound absorption, difficulty in removal, complex preparation, high cost and low yield, short shelf life, high risk of contamination and lack of antibacterial capability, making them unsuitable for large-scale application in the treatment of massive emergency hemorrhaging⁴. In addition, limited research has been reported on hemostatic agents that simulate the treatment of massive human hemorrhage^2-4. 

To overcome these challenges, our team has been working hard to design a high-performance hemostatic sponge (AR50 sponge) that is both biosafe and antibacterial, and meeting the following requirements:

1. strong hemostatic function;
2. suitable mechanical property; 
3. rapid absorption by wound; 
4. efficient antibacterial properties; 
5. cost-effective; 
6. easily fabricated, handled and manipulated; 7
7. stable and long shelf life.  

Nature-Inspired Solution

We realized that despite polysaccharides face challenges such as low hemostatic activity, a short shelf life, a high contamination risk, low coagulation and anti-infection capacities, they have gained attention as clinical frontier hemostatic materials owing to their outstanding biological activities, abundant sources, high biosafety levels and easily modifiable structures, and their derivatives have already widely used in preparing commercial hemostats. Therefore, we contacted Prof. Jianfa Zhang and chose a special polysaccharide, ricin, an extracellular polysaccharide derived from Agrobacterium sp. ZCC3656, exhibits outstanding bioactivity, biocompatibility, and cost efficiency (production yield, 20 g·L^-1), provided by Center for Molecular Metabolism, Nanjing University of Science & Technology. Riclin can generate aldehyde groups after reacting with NaIO₄. After applying the appropriate reaction ratio, we repeatedly freeze-thawed and freeze-dried the product to finally produce AR50 sponge (Figure 1). The relevant project research has been published in “Communications Material”.

Figure. 1 The chemical structure and schematic diagram illustrating the formation of the aldehyde-modified riclin(AR50).

Toward Clinical Translation

Encouraged by in vitro coagulation experiments and efficient hemostatic performance in small animal hemorrhage models, we hoped to advance toward clinical translation by testing AR50 sponge on pre-clinical porcine models. So, we designed hemostasis models of porcine hepatic incision, perforation and femoral artery scission (Figure 2 and 3). After months of experimentation, our hemostasis practice has achieved significant success. On the one hand, AR50 sponge achieves an excellent hemostatic effect at relatively low doses, reducing hemostasis time and blood loss by 80%-90%, are among the best in the evaluation system of hemostatic sponges³. On the other hand, the AR50 sponge could be effortlessly removed from the wound, mitigating the risk of debridement and eliminating the possibility of bacterial infection. All animals survived after the application of AR50 sponge to halt bleeding. Given these remarkable results, we posit that the AR50 sponge could serve as an ideal hemostatic agent for acute traumatic massive hemorrhage scenarios, holding promise in terms of production and application. 

Figure. 2 Hemostasis of massive hemorrhage in the porcine hepatic laceration and perforation model.

Figure. 3 Hemostasis of massive hemorrhage in porcine femoral artery scission model.

The Mechanism Behind Hemostasis

Based on the procoagulant mechanism and superior hemostatic effect of the AR50 sponge, we propose the following unique hemostatic mechanism consisting of three phases as shown in Figure 4:

(Ⅰ) a large number of erythrocytes and platelets are rapidly recruited and targeted to accumulate on the hemostatic surface;

(Ⅱ) at the contact interface, numerous platelets are quickly activated and erythrocytes deform into polyhedral shapes, synergistically forming a robust, stable cell cluster;

(Ⅲ) the quasi-honeycomb channel structure of the sponge itself could partially replace the supporting and pulling effect of fibrin, which combines with the cell clusters composed of erythrocytes and platelets to create a stable hemostatic barrier (i.e., a blood clot) to complete hemostasis in sizable bleeding wounds in large animals.

Additionally, the excellent mechanical properties of shape memory recovery and rapid liquid absorption enable the AR50 sponge to perform effectively in non-compressible wounds.

Figure. 4 Schematic illustration of the hemostatic mechanism of the AR50 sponge for applications in human emergency massive hemorrhage treatment.

Overall, the AR50 sponge provides a practical and robust solution for massive acute hemorrhage. Its ability to combine with other excellent hemostatic materials highlights its potential for future enhancements.

References

1. Fisher, A. D., Bulger, E. M. & Gestring, M. L. Stop the bleeding: educating the public. JAMA,320,589–590 (2018).
2. Hickman, D. S. A., Pawlowski, C. L., Sekhon, U. D. S., Marks, J. & Gupta, A. S. Biomaterials and advanced technologies for hemostatic management of bleeding. Adv. Mater.30,1700859 (2018).
3. Nepal, A., Tran, H., Nguyen, N. T. & Thu Ta, H. Advances in haemostatic sponges: Characteristics and the underlying mechanisms for rapid haemostasis. Bioact. Mater. 27,231–256 (2023).
4. Li, X. et al. Emerging materials for hemostasis. Coord. Chem. Rev. 475,214823 (2023).