Research & Technology

The Company's pre-clinical strategy has been to perform a robust program exploring the FASTCLOT® technology performance in a broad range of hemostasis applications.

Updated summary of preclinical studies for SURGICLOT®

St. Teresa Medical updated summary of Pre-Clinical studies for SURGICLOT® including applications for Dural repair and sternotomies.

 


Dextran as the Dressing Component of FASTCLOT®

Dextran is a branched-chain polysaccharide that has been used in medicine for many decades.  It is available in two forms, the more common “Dextran 40,” commonly 10% dextran, and “Dextran 70,” commonly 6% and 32% dextran.

Most of the medicinal uses of dextran involve intravenous administration of Dextran 40.  Due to its high molecular weight it is an excellent osmotic agent.  Therefore, it is administered intravenously where it acts as a volume expander during hemorrhagic shock.  It is used in this application for both civilian and combat trauma.1,2  It also can be used during elective surgery for volume expansion.

Intravenous administration of Dextran 40 exerts an antithrombotic effect on platelets, endothelium and red blood cells by reducing aggregation and adhesiveness.  Intravascular clots are less likely to form in the presence of dextran.  This property of dextran has made it useful as a prophylactic agent for deep venous thrombosis (DVT) in surgical patients.  It also is used to maintain patency of vessels in procedures that require microanastomosis.

Typical intravenous dosages of dextran are a liter or more on the first day followed by a half a liter for several days.

In addition to intravenous administration, dextran has been used topically.  Gynecological surgeons have used Dextran 70 as an agent of choice when distending the abdomen and pelvis during laparoscopic and hysteroscopic surgery.  Dextran 70 is superior to barriers such as Gelfoam and Surgicel for preventing post-surgical adhesions.3  It also appears to be superior to normal saline.4,5

Generally, from 250 ml to 1 liter of dextran 70 is used for irrigation of the abdomen and pelvis.

The other common topical use of dextran is as a component of ophthalmologic solutions, where it acts as a soothing agent and lubricant.  Dosages are measured in drops.

FASTCLOT® is a hemostatic dressing primarily composed of a dry powder of the clotting proteins fibrinogen and thrombin embedded within a solid dextran dressing.  There are other minor components to the dressing that act as preservatives and stabilizers.

Dextran was chosen for a number of reasons.  First, as a molecule, it is amenable to the process of electrospinning.  Electrospinning creates dry nanofibers of dextran that can be configured into any desired size or shape.  The resulting product, called a “dextran mat,” is highly porous on a nano scale.  The pores of the mat are small enough to contain the protein powder, yet large enough to readily admit water. 

Secondly, dextran is highly soluble in water, so when water, or blood, contacts the mat it quickly dissolves the mat and liberates the proteins.  The dry protein powder solubilizes rapidly, which allows the two clotting proteins to interact, resulting in a stable, tenacious clot.  The process is very rapid, and at the stage of clot formation the dextran has been removed from the area of application.6

Finally, dextran is the ideal dressing material for FASTCLOT® because of its safety profile.  The dextran dosages used in the FASTCLOT® dressings are a fraction of the recommended intravenous use, or the topical intra-abdominal use.  The dose of dextran in FASTCLOT® is proprietary, but is several orders of magnitude less per dressing than what is used intravenously in treatment of shock, DVT prophylaxis, or abdominal irrigation. 

In summary, electrospun dextran is the ideal dressing material in FASTCLOT® because it is safe, it dissolves rapidly, and it does not leave a trace.

FASTCLOT® could become an ideal platform for the delivery of pharmaco-therapeutic agents.  It is possible to embed dry forms of drugs in the FASTCLOT® dressing.  For example, antibiotics could be embedded in the dressing, along with fibrinogen and thrombin.  The antibiotic would then become embedded in the clot and could elute into the tissues over a period of time, delivering antibiotics directly to a wound.  Similarly, it is possible that some chemotherapeutic agents used in cancer treatment could also be embedded in the dressing for local delivery of higher concentrations than could be delivered by intravenous or other methods.

FASTCLOT® is a platform nanotechnology that will have many applications, not only in hemostasis, but as a delivery system for a myriad of medications. (Nanotechnology is the engineering of functional systems at the molecular scale dealing with dimensions and tolerances of less than 100 nanometers, especially the manipulation of individual atoms and molecules.)

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FASTCLOT® is a platform nanotechnology that will have many applications

The Company has completed a total of nineteen (19) pre-clinical studies, performed to both Good Laboratory Practices (GLP) and non-GLP standards. The program was focused in three basic medical areas: (1) spine and orthopaedic procedures; (2) control of high-volume arterial/venous bleeding; and (3) soft tissue / liver & spleen coagulation. The goals of the studies were to determine ideal product configurations and formulations, to develop and hone proper surgical techniques and to determine initial market focus and form the basis for regulatory strategy and filings. Summaries of the more important studies are described below.

This video contains graphic scenes from a surgical procedure. Arterial Bleeding in a Swine Femoral Arteriotomy Model


 

    References

    1. Watters J, Tieu B, Differdin J, et al. 2006. A single bolus of 3% hypertonic saline with 6% destran provides optimal initial resuscitation after uncontrolled hemorrhagic shock. J Trauma and Acute Care Surg 61(1): 75-81.
    2. Dubick M, Atkins JL. 2003. Small-volume fluid resuscitation for the far-forward combat environment: current concepts. J Trauma and Acute Care Surg 54(5):S43-45.
    3. Soules MR, Dennis L, Bosarge A, Moore DE. 1982. The prevention of postoperative pelvic adhesions: an animal study comparing barrier methods with dextran 70.  AJOG 143(7):829-34.
    4. Neuwirth RS, Khalaf SH. 1975. Effect of thirty-two per cent dextran 70 on peritoneal adhesion formation. AJOG 121(3):420-22.
    5. Buttram VC, Malinak R, Cleary R, et al. 1983. Reduction of postoperative pelvic adhesions with intraperitoneal 32% dextran 70: a prospective randomized clinical trial. Fertility and Sterility 40(5):612-19.
    6. Padua RA, Olson CE, Floyd CT.  Resorption characteristics of a novel fibrin hemostatic dressing.  Orthopedic Research Society Annual Meeting, Orlando, 2016.

    GLP Safety and Performance Study Results in Goats

    The purpose of the study was to evaluate the product configuration SURGICLOT's® safety and performance in a goat model of cancellous bone bleeding.

    Injuries were created in the spine and iliac crest of goats. Animals received either manual compression for four minutes with gauze and SURGICLOT® or manual compression for four minutes with gauze alone (control animals). Overall, SURGICLOT® achieved hemostasis in less than four minutes at all injury sites. in a majority of control animals, hemostasis was not achieved even after eight minutes. In these cases, bone wax had to be applied to stop the bleeding. No adverse events associated with SURGICLOT® occurred over the 28-day animal survival period. Macroscopic and histopathology analysis of the injury sites revealed normal inflammatory healing response associated with the surgical procedure and SURGICLOT® resorption. No significant adverse effects were seen. Examination of animal organs revealed no toxic effects associated with SURGICLOT®. Taken together, these results indicate that SURGICLOT® is both safe and effective in promoting hemostasis of cancellous bone bleeding.

    • No immunological cross-reactions
    • No autoimmune responses
    • No development of coagulopathies
    • No increased local inflammatory response
    • No evidence of distal embolization
    • No evidence of abnormal intravascular thrombosis

    GLP Resorption Study in Rats

    A 10x clinical dose of SURGICLOT® was implanted subcutaneously in the dorsal flank of rats. Tissue was examined macroscopically and histologically at 14, 28, and 56 days. No animals reacted adversely to the implanted product, and no product was visible at the implant site. Histological analysis revealed normal inflammatory activity at 14 and 28 days. By 56 days SURGICLOT® was fully resorbed. SURGICLOT® was deemed a "non-irritant". Competitive products, e.g., TachoSil® and EVARREST®, had significant visible product remaining at similar time points.

    GLP Swine Corpectomy Study

    The study used a swine corpectomy (spine) surgery model to demonstrate the efficacy and safety of its SURGICLOT® hemostatic product on bone. A total of six animals were studied, with a total of 36 spine corpectomy surgeries conducted using Gelfoam® as the control product. In the study, SURGICLOT® was superior for every primary endpoint measured. A complete histopathology and pathology analysis indicated no safety concerns.

    Achieving Hemostasis in a Swine Spine Model SURGICLOT® vs. Gelfoam®

      Success Rate
    Parameter SURGICLOT®
    % (n/N)
    Gelfoam®
    % (n/N)
    OR
    (95% CI)
    Test P-Value Criteria for
    Success
    Conclusion
    Hemostasis within 4 Minutes 88.9%
    (16/18)
    11.1%
    (2/18)
    0.02
    (0.00, 0.31)
    Non-Inferiority 0.004 Upper limit of 95% CI for odds ratio < 1.10 Non-Inferiority Achieved
    Superiority 0.006 Upper limit of 95% CI for odds ratio < 1.00 Superiority Achieved

    GLP Brisk Arterial Bleed in Swine Study Results

    An FDA Good Laboratory Practice ("GLP") study was completed in February 2011 and a subsequent coagulopathy study in November 2011.

    The Company utilized a swine femoral bleeding model to demonstrate the safety and efficacy of a hemostatic dressing that contains salmon thrombin and fibrinogen proteins. A total of 20 animals were studied using QuikClot® Combat Gauze as the control product. The WRAPCLOT® hemostatic bandage was superior or better in every primary endpoint and based on complete histopathology and pathology showed no safety concerns. All major organs were investigated in accordance with GLP guidelines.


    The studies showed that the WRAPCLOT® bandage is significantly superior or substantially equivalent to Combat Gauze, used as the control, with respect to overall blood loss, time to hemostasis, survival time and percent survival. In terms of clot formation and stability, the WRAPCLOT® hemostatic bandage was found to be materially superior to Combat Gauze. With respect to safety, the study results showed that the WRAPCLOT® is as safe as the Combat Gauze. Clinical pathology, adverse events, gross necropsy, and histopathology results were equivalent between the products.

    Swine Coagulopathy Femoral Artery Injury Model

    Using the Military Developed Protocol November 2011

    coagulopathy image

    GLP Hemostasis Study in Swine - Dextran alone vs. SURGICLOT®

    In December 2014, a swine model of cancellous bone bleeding was used to demonstrate that the solid electrospun dextran nanofiber dressing contributes primarily to the hemostatic properties of the SURGICLOT® dressing, and that the human thrombin and fibrinogen (clotting proteins) embedded in the SURGICLOT® dressing act ancillary to enhance the hemostatic effect of the dextran.

    Bone injures were created in the right and left iliac crests, and in the right and left sides of the posterior aspect of L6-L4 vertebrae. Upon creation of a blood-oozing bone decortication injury, a 5 minute pre-treatment free-bleed was observed prior to treating with either a dextran-only or SURGICLOT® dressing. Following the initial dressing application, the injuries were assessed for hemostasis at 2-minutes. If hemostasis did not occur after the initial 2-minute application, the dressing was re-applied for an additional 2-minutes. No injury was treated for longer than a total of 4 minutes.

    The results of this study showed that both the dextran-only and SURGICLOT® dressings achieved hemostasis of all injuries. The injuries treated with the dextran-only bandage achieved hemostasis in 40% (4 of 10) of the injuries after initial application (2-minute duration), and after reapplication in 60% (6 of 10) of the injuries. In contrast, all injuries (10 of 10) treated with the SURGICLOT® dressing achieved hemostasis after initial application. Spontaneous hemostasis did not occur in any of the injuries after the 5-minute pre-treatment free-bleed. The faster time to hemostasis elicited by the SURGICLOT® dressing as compared to that of the dextran-only dressing indicates that the human plasma proteins embedded in the SURGICLOT® dressing acts to enhance the dextran dressing's hemostatic effect. Moreover, the free-bleed results showed that the cancellous bone injuries were severe enough such that hemostasis could not be achieved without application of either dressing. Thus, the study was successful in demonstrating that the primary mode of action of the SURGICLOT® to achieve hemostasis is contact of the electrospun dextran with the cancellous bone bleeding site followed by an ancillary effect of the clotting proteins embedded in the SURGICLOT® dressing to enable hemostasis to be achieved faster.

    Swine Liver Pre-Clinical Study

    In June 2012, the Company had an independent study performed using a swine liver injury model to demonstrate the efficacy and safety of its SURGICLOT® hemostatic product on soft-tissue injuries like the liver.

    The liver injury model is considered a gold-standard test when evaluating hemostatic agents, surgical applications, dressings and treatment methods for severe hepatic injury. A total of six animals were studied, with each animal receiving 18 liver injuries, three from each product, and using TachoSil® as the control product. SURGICLOT® was superior for every primary endpoint measured. Complete histopathology and pathology analysis indicated no safety concerns.

    ACHIEVING HEMOSTASIS IN A SWINE LIVER MODEL SURGICLOT® VS TACHOSIL®

    18 Liver Injuries Made and 18 Initial 20-Second Compressions Performed per Product


    Hemostasis graph image

    Swine Corpectomy Study

    In February 2013, the Company had an independent study performed, also by NAMSA, an independent clinical and pre-clinical regulatory-certified FDA laboratory. The study used a swine corpectomy (spine) surgery model to demonstrate the efficacy and safety of its SURGICLOT® hemostatic product on bone. A total of six animals were studied, with a total of 36 spine corpectomy surgeries conducted using Gelfoam® as the control product. In the study, SURGICLOT® was superior for every primary endpoint measured. A complete histopathology and pathology analysis indicated no safety concerns.

    GLP Dural Repair Studies in Goats and Sheep

    During spinal or cranial surgery, the dura (the watertight membrane encasing the spinal cord and cranium) can be opened. When that happens, spinal or central nervous system (CNS) fluid starts to leak. Whether this opening is planned or an unplanned surgical complication, the surgery cannot be completed until this opening is repaired.

    The Company conducted a 30-day survival study in goats. Each goat had its spinal cord exposed and then received a 4mm incision in the dura (a durotomy), causing cerebral spinal fluid (CSF) to leak. The cut was closed by placing one of our new 1.25” x1.25” sized dressings on the wound. The leaking CSF activated the fibrinogen and thrombin and the resulting fibrin sealed the wound. After five minutes, the seal was successfully tested with the Valsalva maneuver (simulating the effect of coughing or vomiting during recovery). The surgery site was closed and animals returned to their pens. After 30 days, the goats were sacrificed. Each durotomy site was inspected and healing was determined to be normal, gross pathology revealed no excessive fibrosis or inflammation, and more importantly no evidence of further CSF leakage. Each wound site was tested for integrity; the thecal sac was tied off above and below the injury site, then injected with methylene blue into the sac at pressures exceeding 200 cm of H20. No leakage was observed. The spine sections were sent out for histopathology analysis. No abnormal pathologies were found in the analysis.

    In a second study in sheep, SURGICLOT® controlled CSF leaks in 20 of 20 cranial durotomies (100%), while suture alone, which is the current standard of care, controlled CSF (Cranial Spinal Fluid) leaks in only 3 of 23 (13%) cases. These studies showed that SURGICLOT® is safe and effective at controlling CSF leaks following spine and cranial durotomies. The results have been submitted to the Congress of Neurological Surgeons.

    Dural Repair photo
    Dural Repair photo

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