Systematic review: Advances of fat tissue engineering as bioactive scaffold, bioactive material, and source for adipose-derived mesenchymal stem cells in wound and scar treatment

Fat tissue (FT) has been used for many years in regenerative surgery as a bioactive material through the lipofilling/fat graft (F-GRF)-nano-fat technique, as a bioactive scaffold when it was enriched with adipose-derived mesenchymal stem cells (AD-MSCs) contained in the stromal vascular fraction (SVF), and as a direct source of AD-MSCs used in wound healing (WH) and scar treatment (ST). This systematic review aims to describe the advances in FT engineering applied to regenerative surgery (from bench to clinic), through the use of AD-MSCs, SVF contained in F-GRF in WH and ST. The work has been performed by assessing in the selected studies autologous graft of AD-MSCs, SVF, and F-GRF compared to any control for ST and WH. The protocol was developed following the Preferred Reporting for Items for Systematic Reviews and Meta-Analyses-Protocols (PRISMA-P) guidelines. A multistep search of the PubMed, MEDLINE, Embase, PreMEDLINE, Ebase, CINAHL, PsycINFO, Clinicaltrials.gov , Scopus database, and Cochrane databases has been performed to identify papers on AD-MSCs, SVF, and F-GRF use in WH and ST in which FT was used as bioactive material-scaffold and source of AD-MSCs. Of the 714 articles initially identified, 453 articles focusing on regenerative strategies in WH and ST were selected and, consequently, only 84 articles that apparently related to AD-MSC, SVF, and F-GRF were analyzed. Of these, 61 articles identified as pre-clinical, experimental, and in vitro, and 5 articles identified as a comment and systematic review were excluded. Only 18 original articles which strictly and exclusively focused on autologous AD-MSCs, SVF, and F-GRF in ST and WH were analyzed. The included studies had to match predetermined criteria according to the PICOS (patients, intervention, comparator, outcomes, and study design) approach. The identified studies described microscopic and clinical outcomes in patients treated with AD-MSCs, SVF, and F-GRF. Collected data confirmed the safety and efficacy of FT both as bioactive material-scaffold and source of AD-MSCs in WH and ST without major side effects.

Gentle Is Better: The Original "Gentle Technique" for Fat Placement in Breast Lipofilling

CONTEXT

Breast lipofilling usually involves three different stages (harvesting, processing, and placement), and in each of these phases, adipocyte cells can be damaged. Our technique of fat placement is quite different from the others as we focus our attention on the last stage of fat graft procedure, which could explain the better results in graft survival.

AIMS

Our method is focused on eliminating any unnecessary manipulation of the graft so as to optimize graft retention and clinical outcomes: Controlled movement and slow rate of fat injection are the cornerstone of our technique and guarantee a nontraumatic fat transfer and a greater survival rate of adipocytes.

SETTINGS AND DESIGN

This was a retrospective cohort study.

MATERIALS AND METHODS

Of 120 patients (average age 41,5 years) affected by breast soft tissue defects, 60 were managed with the lipofilling procedure using fat graft injected by "Gentle technique." To establish the effects of the injection's procedure, we compared the results obtained in fat graft maintenance with a control group made up of 60 patients, treated with fat graft injection according to Coleman procedure.

STATISTICAL ANALYSIS USED

Values are expressed as mean plus standard error and analyzed using Student's t test.

RESULTS

In patients treated with Gentle technique, we observed a 60.5% + 12.5% maintenance of contour restoring and three-dimensional volume after 1 year (P < 0.0001 vs. control group); we compared the results obtained with only 39% + 4.4% of the control group treated with fat graft injected according to Coleman.

CONCLUSIONS

Controlled 26 movement and slow rate of fat injection are the cornerstone of our technique and guarantee a nontraumatic fat transfer and a greater 27 survival rate of adipocytes.

Adipose-Derived Mesenchymal Stem Cells (AD-MSCs) against Ultraviolet (UV) Radiation Effects and the Skin Photoaging

The skin is a natural barrier against the ultraviolet (UV) radiation of sunlight. The long-term and/or repetitive exposure to the sunlight and related UV radiation may change the skin structure, decreasing collagen production, promoting premature skin aging, which is termed "photoaging". The signs of photoaging include wrinkle formation, mottled pigmentation, and/or cancerous changes. For many years, adipose-derived mesenchymal stem cells (AD-MSCs) and fat grafting (F-GRF) have been used to combat photoaging signs, wrinkles, loss of elasticity, and face soft tissue defects. Several studies have analyzed in vitro actions of AD-MSCs against photoaging's effects, thanks to their migratory activity, paracrine actions, and related in vivo-ex vivo outcomes. In fact, AD-MSCs act against skin photoaging in vitro via activation of dermal fibroblast proliferation, antioxidant effect, and matrix metalloproteinases (MMPs) reduction. In vivo and ex vivo outcomes regard the local injection of AD-MSCs, F-GRF, and/or enriched-F-GRF with AD-MSCs directly in the wrinkles and the face's soft tissue defects. This concise review summarizes the most recent in vitro, in vivo and ex vivo outcomes and developments on the effects of AD-MSCs and F-GRF against photoaging.

Reconstruction of Alar Nasal Cartilage Defects Using a Tissue Engineering Technique Based on a Combined Use of Autologous Chondrocyte Micrografts and Platelet-rich Plasma: Preliminary Clinical and Instrumental Evaluation

BACKGROUND

Developing cartilage constructs with injectability, appropriate matrix composition, and persistent cartilaginous phenotype remains an enduring challenge in cartilage repair. The combined use of autologous chondrocyte micrografts and platelet-rich plasma (PRP) is an alternative that opens a new era in this field.

METHODS

At the Department of Plastic and Reconstructive Surgery, University of Rome Tor Vergata, Italy, 11 patients underwent nasal alar reconstruction with chondrocyte micrografts gently poured onto PRP in solid form. A computed tomographic scan control was performed after 12 months. Pearson's Chi-square test was used to investigate difference in cartilage density between native and newly formed cartilages.

RESULTS

The constructs of chondrocyte micrografts-PRP that were subcutaneously injected resulted in a persistent cartilage tissue with appropriate morphology, adequate central nutritional perfusion without central necrosis or ossification, and further augmented nasal dorsum without obvious contraction and deformation.

CONCLUSION

This report demonstrated that chondrocyte micrografts derived from nasal septum poured onto PRP in solid form are useful for cartilage regeneration in patients with external nasal valve collapse.

Vasculogenic Chronic Ulcer: Tissue Regeneration with an Innovative Dermal Substitute

The healing of venous and arterial ulcers is slow, and in some cases, they may not heal at all. This study aims to demonstrate the clinical advantage of Nevelia®, an innovative collagen dermal template substitute (DS) in venous and arterial chronic ulcers treatment. 35 patients affected by chronic vascular ulcers with a mean area of 35.1 ± 31.8 cm2 were treated with DS followed by autologous dermal epidermal graft (DEG). Follow-up was performed at 7-14-21 and 28 days after DS implant and 7-14-21 and 28 days after DEG. At 28 days after DEG, the mean values of Manchester Scar Scale was of 1.8 ± 0.7 for skin color, 1.6 ± 0.7 for skin contour, 1.7 ± 0.7 for distortion, and 1.7 ± 0.7 for skin texture, whereas skin was matte in 27 patients (77%) and shiny in the remaining eight cases (23%). Histological findings correlate with the clinical result showing a regenerated skin with reactive epidermal hyperplasia and dermal granulation tissue after two weeks (T1), and after three weeks (T2) a re-epithelialization and a formed new tissue architecture analogue to normal skin physiology. These data suggest that Nevelia® could be useful to treat chronic venous and arterial ulcers.

SARS-CoV-2: the "Uncensored" Truth about Its Origin and Adipose-Derived Mesenchymal Stem Cells as New Potential Immune-Modulatory Weapon

In this second return of the pandemic, January 2021, it appears to be clear that a Nano-sized organism, the SARS-CoV-2, has rendered the human race helpless, made the global health status decline, and drowned the world economy. However, it does not appear clear the real origin of the SARS-CoV-2 and the aim of this work is to report and discuss, maybe for the first time since the pandemic began, the scientific data published in this specific field, analyzing the potentially available weapons against the SARS-CoV-2. About this last point, a ray of hope comes from the potential of Mesenchymal Stem Cells (MSCs) that has already been established in Coronavirus Disease 2019 (COVID-19), and in particular from the Adipose-Derived Mesenchymal Stem Cells (AD-MSCs). However, cell-based therapy has its own limits, especially represented by the know-how in this field and by the rules of applications. It was suggested a biological therapy using AD-MSCs as a weapon against COVID-19, as they can be a game-changer owing to their immuno-modulatory nature, which combats the cytokine storm characterizing this disease, and their practical efficiency, which will realistically aid large access to therapy worldwide.

Titanium-coated polypropylene mesh as innovative bioactive material in conservatives mastectomies and pre-pectoral breast reconstruction

Breast reconstruction is rapidly evolving, thanks to the growing acceptance of synthetic meshes as innovative biomaterials. 276 patients undergoing mastectomy (total of 328 mastectomies) were analyzed in a retrospective observational study to evaluate the pre-pectoral immediate breast reconstruction (IBR) using an implant wrapped with Titanium-Coated Polypropylene Mesh (TCPM) vs. patients treated with tissue expander (TE), equally placed pre-pectorally (and wrapped with the same TCPM in 74.3% of the control group' breasts). 163 patients, of the study group (SG), underwent mastectomy and pre-pectoral IBR with implant wrapped with TCPM, in a one-step surgery, called direct-to-implant technique (DTI), while 113 patients control group (CG) underwent mastectomy and TE. DTI technique has been performed in 192 breasts of the SG while TE procedure in 136 breasts of the CG. The BREAST-Q questionnaire has been provided before the treatment and 2 years later. Baker scale has been used to evaluate capsular contracture. Oncologic, surgical, and aesthetic outcomes along with BREAST-Q scores were analyzed. Additionally, a histologic evaluation was conducted in 11 capsules' samples randomly chosen (6 derived from SG patients and 5 derived from CG). Complications were recorded in 43 cases (29SG-14CG): 8 skin-nipple necrosis (5SG-3CG), 8 wound dehiscence (6SG-2CG), 3 hematomas (1SG-2CG), and 24 infections (8SG-16CG). Grade IV capsular contracture was detected in 9 breasts (1SG-8CG), whereas 254 breasts were grade I (110SG-144CG), 33 (10SG-23CG) grade II, and 32 (4SG-28CG) grade III. Implant wrinkling was detected in 18 cases (10SG-8CG) after 30 months. The local tumor recurrence rate was 5.8%. Three recurrences were on the nipple-areola complex (1.9%). SG patients showed significantly higher rates in the BREAST-Q overall Satisfaction with Outcome (74.1), overall Satisfaction with Breasts (69.1), Psychosocial Well-being (81.9), and Sexual Well-being (63.1), versus CG's patients (p < 0.05). Histological analysis showed a process of normal tissue repair with a complete mesh integration and normal healing. Conservative mastectomies with pre-pectoral IBR assisted by TCPM proved themselves oncologically safe, biologically integrated into native tissues, and highly accepted in terms of quality of life guaranteeing a more natural and aesthetic breast appearance.

CORE TIP

This retrospective observational study provided clinical and histological outcomes of the pre-pectoral IBR using an implant wrapped with TCPM vs. patients treated with TE, equally placed pre-pectorally. The efficacy of IBR using an implant wrapped with TCPM was confirmed by the cosmetic results obtained and by a rate of side effects comparable to TE. All the histological analyses performed confirmed the TCPM mesh complete integration with the physiological aspects of healing: The Collagen 1 and 3 expressions did not differ, between TCPM and NO TCPM samples to confirm a process of healing overlapping to perfect device incorporation and normal healing.

Tuberous Breast, Deformities, and Asymmetries: A Retrospective Analysis Comparing Fat Grafting Versus Mastopexy and Breast Implants

BACKGROUND

The tuberous breast is considered a breast deformity characterized by varying degrees of herniation of the parenchyma, widened nipple-areolar complex (NAC), absence of the lower quadrants, and may involve several degrees of hypoplasia and asymmetry causing significant psychosocial distress.

OBJECTIVES

The paper aimed to compare the results obtained in patients suffering tuberous breast treated with fat grafting (FG), with those of patients treated with a mastopexy and silicone implants (M-SI) also analyzing the influence of breast and chest deformities (degrees of hypoplasia and tuberous breast, volume and NAC asymmetry, pectus excavatum, and carinatum) in the reconstructive outcomes.

METHODS

A retrospective, case-control study was conducted. Thirty-five patients affected by tuberous breast with several degrees of hypoplasia and asymmetry were treated with FG, comparing results with those of 30 patients treated with M-SI. Postoperative follow-up took place at 1, 3, 7, 12, 24, 48, weeks, and then annually for 2 years.

RESULTS

77% (n = 27) of patients treated with two FG procedures showed excellent results after 1 year compared with the patients treated with only one M-SI procedure, who showed the same results in 73% (n = 22) of cases, but the naturalness and the satisfaction degree in the FG group were higher than that in the M-SI group (p < .0001 vs. M-SI group).

CONCLUSIONS

Patients treated with FG showed natural breasts without scars and excellent cosmetic results after two procedures. Patients treated with M-SI showed more evident and lasting results after only one procedure, presenting though scars and less natural results.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Fluid Cartilage as New Autologous Biomaterial in the Treatment of Minor Nose Defects: Clinical and Microscopic Difference Amongst Diced, Crushed, and Fluid Cartilage

Developing cartilage constructs with injectability, appropriate matrix composition, and persistent cartilaginous phenotype remains an enduring challenge in cartilage repair. Fourteen patients with minor contour deformity were treated with fluid cartilage filler gently injected as autologous fluid graft in deep planes of defect of the nose that were close to the bone or the cartilage. A computerized tomographic scan control was performed after 12 months. Pearson's Chi-square test was used to investigate differences in cartilage density between native and newly formed cartilages. The endpoints were the possibility of using fluid cartilage as filler with aesthetic and functional improvement and versatility. Patients were followed up for two years. The constructs of fluid cartilage graft that were injected in the deep plane resulted in a persistent cartilage tissue with appropriate morphology, adequate central nutritional perfusion without central necrosis or ossification, and further augmented nasal dorsum without obvious contraction and deformation. This report demonstrated that fluid cartilage grafts are useful for cartilage regeneration in patients with outcomes of rhinoplasty, internal nasal valve collapse, and minor congenital nose aesthetics deformity.

Obesity phenotypes and resorption percentage after breast autologous fat grafting: Rule of low-grade inflammation

BACKGROUND

One of the main reasons why the breast fat grafting was questioned is that there may be lipofilling resorption. In the literature, the resorption rate reported over the 1(st) year is highly variable (20-90%).

OBJECTIVE

The aim of this work was to identify the biochemical and clinical parameters, which increase fat graft maintenance in breast reconstruction.

MATERIALS AND METHODS

A sample of 19 patients was treated with fat grafting mixed with platelet-rich plasma. A complete screening of anthropometry, body composition, and blood biochemical parameters was assessed using the standardized equipment. Pre- and post-operative evaluation was performed, which included a complete clinical examination, photographic assessment, nuclear magnetic resonance imaging of the soft tissue, and ultrasound. The follow-up period was 2 years.

RESULTS

The authors divided the results into two types of patients: "responder" and "not a responder." In the "responder" group patients with normal weight, gynoid fat distribution, obese, with normal blood biochemical parameters, and atherogenic indices but with high preoperative values of platelet-to-lymphocyte ratio (PLR) (174.49) and neutrophil-lymphocyte ratio (NLR) (2.65) showed a greater increase of fat graft maintenance at 6 and 12 months after the last lipofilling session. In the "not responder group" patients with overweight, android fat distribution, obese, high values of atherogenic indices, but with normal preoperative NLR and PLR ratios showed a lower fat graft maintenance at 6 and 12 months.

CONCLUSION

We assume, the problem of fat resorption may be resolved by analysis of body composition and by examine the predictive role of preoperative markers of low-grade inflammation.

Malignant Skin Cancer Excision in Combined Therapy with Electro-Chemotherapy and Dermal Substitute

Squamous cell carcinoma (SCC) is the second most common malignancy skin cancer. It is characterized by abnormal, accelerated growth of squamous cells (SCs). SCC occurs when DNA damage from exposure to ultraviolet radiation or other damaging agents trigger abnormal changes in the SCs, presenting as painless lesions on areas of high sun exposure, such as the dorsum of the hand and upper extremity. For most skin SCC, the surgical excision alone is standard practice. However, recent efforts in new treatment strategies have involved around adjuvant or concomitant electrochemotherapy (ECT). ECT is a non-thermal tumor ablation modality, safe and effective on any type of solid tumor. An 87-year-old patient affected by hand SCC with invasion of deep structures including tendons was treated with neoadjuvant intra-tumoral ECT sessions followed by a selective surgical removal and reconstruction of the substance loss with collagen dermal template (CDT). Two neoadjuvant intra-tumoral ECT procedures, at distance of 3 months, with the aim to reduce the tumor size before a selective surgery, were performed. This study shows that combined surgical selective excision with ECT and CDT is a valid technique for the extended-deep dorsal hand tumor lesions reconstruction.

Medial Thigh Contouring in Massive Weight Loss: A Liposuction-Assisted Medial Thigh Lift

BACKGROUND

Thigh's lifting can be associated with significant complications, if the medial thigh excess is removed en bloc. In this study, the liposuction-assisted medial thigh's lift (LAMeT) procedure, outcomes and complications were assessed.

METHODS

Twenty four females between 25 and 61 years with grade 2 or 3 on Pittsburgh Rating Scale (PRS) treated with medial thigh's reduction were enrolled. Medial thigh's reduction was performed in three different procedures of vertical, horizontal and LAMeT. Vertical thigh's lift with fascia suspension was conducted in 13 patients with grade 3 of ptosis on PRS; horizontal thigh's lift with fascia suspension was undertaken in 3 patients with grade 2 on PRS; vertical and horizontal thigh's lift considered as control group was described as excision-only group; and LAMeT was performed in 8 patients with grade 2 and 3 on PRS.

RESULTS

Complications were observed in 62.5% of patients who underwent vertical or horizontal thigh's lift with fascia suspension and in 16.7% who experienced the LAMeT without fascia suspension. The most frequent complication was seroma. Hospital stay was significantly lower in the LAMeT.

CONCLUSION

Medial thigh's lift is a safe and satisfying procedure because it provides aesthetic improvement in massive weight loss patients. The complication rate is higher when skin excess and laxity are removed en bloc, as the resection of excess tissue is poorly selective. The LAMeT preserves lymphatic and blood vessels and allows a more anatomical resection of the excess skin. Thus postoperative complications incidence is lower and the patient heals faster.

Systematic review: Impact of stem cells-based therapy, and platelet-rich plasma in hair loss and telogen effluvium related to COVID-19

BACKGROUND

The incidence of hair loss (HL) and telogen effluvium (TE) in COVID-19 patients has been reported in several studies.

OBJECTIVES

Evaluate both the increased incidence of HL and TE in COVID-19 and the effectiveness of Platelet-Rich Plasma (PRP), Adipose-derived Mesenchymal Stem Cells (AD-MSCs), and Human Follicle Stem Cells (HFSCs) in these patients.

METHODS

The protocol was developed by the Preferred Reporting for Items for Systematic Reviews and Meta-Analyses-Protocols (PRISMA-P) guidelines. A multistep search of PubMed, MEDLINE, Embase, Clinicaltrials. gov, Scopus, and Cochrane databases has been performed to identify papers focusing on HL and TE COVID-19 related, and papers focusing on AD-MSCs, HFSC, and PRP use.

RESULTS

Of the 404 articles initially identified focusing on HL and TE, 44 were related to COVID-19, and finally, only 6 were analyzed. On the other way, 331 articles focusing on AD-MSCs, HFSC, and PRP were initially identified. Of these, only 6 articles PRP (n = 3), AD-MSCs, and HFSCs (n = 3) have been analyzed.

CONCLUSION

Collected data confirmed both an increased incidence of HL and TE in COVID-19 patients, preliminarily, the related effectiveness of AD-MSCs, HFSCs, and PRP without major side effects.

Mechanical Purification of Lipofilling: The Relationship Between Cell Yield, Cell Growth, and Fat Volume Maintenance

BACKGROUND

The mechanical manipulations of fat tissue represented from centrifugation, filtration, washing, and fragmentation were considered the most effective strategies aiming to obtain purified lipofilling with different impacts both in terms of adipose-derived stem cells amount contained in stromal vascular fraction, and fat volume maintenance.

OBJECTIVES

The present work aimed to report results in fat volume maintenance obtained by lipofilling purification based on the combined use of washing and filtration, in a clinical study, and to deeply investigate the adipose-derived stem cells yield and growth capacity of the different stromal vascular fraction extraction techniques with an in vitro approach.

METHODS

A preliminary prospective, case-control study was conducted. 20 patients affected by face and breast soft tissue defects were treated with lipofilling and divided into two groups: n = 10 patients (study group) were treated with lipofilling obtained by washing and filtration procedures, while n = 10 (control group) were treated with lipofilling obtained by centrifugation according to the Coleman technique. 6 months after the lipofilling, the volume maintenance percentage was analyzed by clinical picture and magnetic resonance imaging comparisons. Additionally, extracted stromal vascular fraction cells were also in vitro analyzed in terms of adipose-derived stem cell yield and growth capacity.

RESULTS

A 69% ± 5.0% maintenance of fat volume after 6 months was observed in the study group, compared with 44% ± 5.5% in the control group. Moreover, the cellular yield of the control group resulted in 267,000 ± 94,107 adipose-derived stem cells/mL, while the study group resulted in 528,895 ± 115,853 adipose-derived stem cells /mL, with a p-value = 0.1805. Interestingly, the study group showed a fold increase in cell growth of 6758 ± 0.7122, while the control group resulted in 3888 ± 0.3078, with a p < 0.05 (p = 0.0122).

CONCLUSIONS

The comparison of both groups indicated that washing and filtration were a better efficient system in lipofilling preparation, compared to centrifugation, both in terms of volume maintenance and adipose-derived stem cell growth ability.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266 .

Use of Platelet Rich Plasma and Hyaluronic Acid in the Treatment of Complications of Achilles Tendon Reconstruction

BACKGROUND

The platelet-rich plasma (PRP) and hyaluronic acid (HA) constitute a system of tissue growth that can regenerate damaged tissue. This study was performed to evaluate the effect of PRP and HA in treatment of complications of Achilles tendon reconstruction.

METHODS

We selected ten patients affected by Achilles tendon injuries resulting from post-surgical complications subsequent to tenorrhaphy and have treated them with autologous PRP in combination with HA to evaluate the improvement of lesions with wound closure.

RESULTS

The treatment with PRP and HA for post-surgical complications of Achilles tendon was effective in healing and regeneration of soft and hard tissues. The healing time was shortened, and the treated area preserved a satisfying strength in plantar flexion and extension of the ankle, denoting to a decisive improvement in texture and a more rapid healing and a good cutaneous elasticity, with a significant reduction of the costs of hospitalization and the pain already the immediate postoperatively. The functional rehabilitation in terms of deambulation and joint mobility was complete.

CONCLUSION

The treatment we proposed allowed an easier and more rapid wound closure with excellent aesthetic improvement. Furthermore, the minimally invasive technique is well tolerated by patients.

Comparison of commercial fibrin sealants in facelift surgery: a prospective study

BACKGROUND

The aim of this study was to compare the effects of two types of fibrin glue in patients undergoing facelift surgery.

METHODS

A prospective, controlled "right-left side" study was carried out in 20 patients. The two fibrin sealants used were Quixil® and Tissucol®. The two sealants were used at the same time, ie, one on one side of the face and the other on the contralateral side. Comparisons were made with regard to rates of hematoma and seroma, degree of induration, edema, ecchymosis, pain levels, and patient satisfaction.

RESULTS

The results were almost equivalent. The only exception was a significant (40 mL) hematoma in a patient treated with Quixil. Bleeding was most likely due to a sudden rise in blood pressure during the immediate postoperative period. However, it must be emphasized that, while Tissucol actually seals the undermined area, thus virtually eliminating the dead space, Quixil acts differently, in that its effectiveness in preventing hematoma is linked mainly to its hemostatic effect.

CONCLUSION

The two fibrin sealants used were nearly identical with regard to patient safety and quality of the result. Nevertheless, it is noted that, while Tissucol has both hemostatic and "gluing" effects, Quixil is mainly effective in securing hemostasis.