Use of Liquid Concentrated Growth Factor in the Management of Necrotic Tissue After Facial Vascular Complications Induced by Hyaluronic Acid Injection

Facial rejuvenation is a cosmetic procedure for which HA has been gaining in popularity among those seeking beauty treatments. In 2018, nearly 2.7 million HA filler injections were performed in the United States.¹ As the number and complexity of dermal fillers increase, the incidence of vascular occlusions will likely increase as well. The overall incidence of vascular adverse events is reportedly 1%.² Among these complications, vascular complication-induced local skin ischemia and necrosis, blindness, and cerebrovascular accidents are the most severe.^3-5

The clinical presentations of facial vascular embolism following HA injection mainly include severe pain and map-like discoloration in the region of the embolism. The damaged or necrotic skin tissues and dermal cells may slough off 48 to 72 hours after ischemia, followed by ulceration. The characteristics of skin damage manifestations, including hyperemia, edema, cyanosis, map-like discoloration, sporadic pointed pustules, necrosis, and ulcer, may vary according to wound depth.⁶ Ischemic skin wounds caused by vascular embolism after HA injection are similar to skin flap damage induced by blood flow obstruction; the clinical treatment of these wounds is rather difficult.

Studies have demonstrated that the application of various growth factors, including VEGF, bFGF, and keratinocyte growth factor, substantially increase ischemic flap survival.^7-10 However, most growth factors have pleiotropic effects and a short half-life, which limits the clinical applications of a single growth factor in managing the ischemic damage to skin flaps.¹¹

CGF is a platelet concentrate comprising various growth factors, platelets, leukocytes, CD34 cells, and fibrinous matrix.^12-14 It accelerates wound healing, and CGF has been applied in clinical practice to promote healing of refractory wounds.^15-17

In the current case series, liquid CGF was applied in the management of necrotic facial wounds caused by vascular embolism following HA injection. This is a newer nonsurgical method for treating tissue necrosis caused by facial vascular embolism after injection of dermal fillers.

Patient selection

A total of 12 patients with tissue necrosis due to blood supply disorders following HA injection who were transferred from other hospitals between February 2017 and August 2020 were included in this study. The time from facial injection of HA to admission to the authors’ hospital was 2 to 5 days (mean ± standard deviation, 3.50 days ± 1.09). All patients reported that they had previously received an injection of hyaluronidase (dose of 400 –1500 U) at other hospitals.

The inclusion criteria included facial injection of HA, facial vascular embolism and skin necrosis, and timely follow-up. Patients with severe complications, such as blindness, hemiplegia, aphasia, and disturbance of consciousness, were excluded.

Treatment methods

Immediately after admission, all patients received a routine injection of hyaluronidase (400–1500 U) at the site of ischemia to prevent expansion of the wound.

The liquid CGF was prepared using a Vacuette (Greiner Bio-One GmbH) negative pressure vacuum collection tube (9-mL green tube) to collect venous blood from the patient. The tube was centrifuged for 13 minutes (Medifuge; Silfradent) using the default program—acceleration for 30 seconds to achieve 2700 rpm, followed by centrifugation at 2700 rpm for 2 minutes, decreased to 2400 rpm for 4 minutes, increased to 2700 rpm for 4 minutes, increased to 3300 rpm for 3 minutes, and finally, decreased over 36 seconds until stopping. The blood was then separated into the following 3 layers: upper (serum), middle (liquid CGF), and lower (red blood cells) (Figure 1). The liquid CGF was acquired and injected into the patients within a span of 15 minutes.

A 1-mL syringe with a 30-gauge needle was used for subcutaneous injection of CGF into the damaged and adjacent areas (Figure 2). For patients whose wounds did not heal with 1 injection, repeat injection was administered once weekly with freshly prepared CGF until wound healing.

Antibiotics were administered routinely for 3 days to prevent infection. For patients with evident infection, antibiotics were administered for 7 days.

Complete recovery of the ulcer caused by facial vascular embolism constituted complete wound healing. A skin wound that decreased in size but did not heal completely (eg, no cyanosis, but slight change in map-like discoloration) was classified as improved. Treatment was noneffective if the skin ulcer did not decrease or expand, and cyanosis and map-like discoloration persisted. Outcomes were assessed 4 weeks after initial (or only) treatment. Time to complete wound healing was the time from the beginning of treatment to complete healing of the ulcer at the site of the ischemic area. The rate of complete healing was calculated as follows: complete wound healing = number of patients with complete wound healing / total number of patients × 100%.

This study was approved by the Ethics Committee of the authors’ institution. All patients signed informed consent forms before participation in the study.

Eleven of the 12 patients with vascular embolism due to facial injection of HA were female, and 1 was male. The mean age of the cohort was 33.25 years ± 6.81 (range, 26–50 years). The sites of HA injection were as follows: nasolabial groove (n = 7), nose (n = 2), intercilium area (n = 1), lacrimal sulcus (n = 1), temporal area (n = 1), and mental area (n = 1). The sites of skin necrosis were as follows: upper lip and nosal ala (n = 6 [50%]); nose tip, nosal ala, and upper lip (n = 1 [8.3%]); upper lip (n = 1 [8.3%]); nose and forehead (n = 1 [8.3%]); lip and mental area (n = 1 [8.3%]); left infraorbital area (n = 1 [8.3%]); and temporal and postauricular area (n = 1 [8.3%]).

Wounds were also classified as mild, moderate, or severe based on the depth of facial skin necrosis. Mild necrosis (superficial injury) was characterized by red and swollen skin, as well as blister formation (n = 2); moderate necrosis (dermal injury) was characterized by map-like discoloration of the ischemic skin, accompanied by sporadic pointed pus and superficial ulcer (n = 3); and severe necrosis (injuries of full-layer skin and subcutaneous tissues) was characterized by cyanosis, large ulcer, black skin, or dark crust of the ischemic skin (n = 7).

The time between the occurrence of facial skin embolism and referral to the authors’ hospital for treatment ranged from 2 to 5 days (3.50 days ± 1.09). The time and dose of hyaluronidase injection in other hospitals were unknown for all patients. Most patients presented with moderate or severe skin necrosis (Table). Two patients presented with necrosis in only 1 site (infraorbital area and upper lip in 1 patient each), and 10 patients presented with necrosis in 2 to 3 sites, indicating that skin ischemia extended beyond the areas innervated by the occluded major blood vessel and had spread to adjacent areas (Figure 3).

No infection, expansion of the necrotic area, or aggravation of the wound was detected in any patient. One to 3 CGF treatments were administered (2.58 ± 0.67). Time to complete wound healing ranged from 20 to 35 days (26.08 days ± 3.63). At 4 weeks after the initial CGF treatment, the rate of complete wound healing was 91.67%. No scar was evident in patients with mild to moderate necrosis (Figure 4); however, patients with moderate wounds exhibited different degrees of scarring after wound healing (Figure 5). Patients with severe necrosis had evident scars (Figure 6). Satisfactory results were achieved in all patients (Figures 3–6). This case series demonstrated that CGF treatment promotes and accelerates wound healing.

The relatively slow rate of wound repair (approximately 20–90 days) following conventional application of hyaluronidase to treat facial skin necrosis induced by vascular embolism after HA injection indicates that continuous induction and stimulation of growth factors in the microenvironment is required for wound healing.¹⁸ In the current study, CGF was injected into the ischemic facial tissues, which provided various exogenous growth factors, promoted vascularization of the ischemic tissues and regeneration of necrotic tissues, and accelerated wound healing. The time to wound healing in this study was 20 to 35 days (mean, 24.08 days), which was considerably shorter than the time to healing following a simple injection of hyaluronidase reported by Ors.¹⁸

The authors of the current study hypothesized that patients with vascular embolism caused by HA injection should be treated with CGF as well as hyaluronidase to accelerate wound healing while resolving emboli. Additional advantages of CGF therapy are its rapid preparation time, safety, noninvasive application, and capacity for repeated use. CGF can be prepared by a single centrifugation of approximately 15 minutes. Because it is prepared using autologous venous blood, there is no risk of rejection or allergic reaction. No chemical agents (eg, thrombase, calcium dichloride) are required to stimulate platelet activation; instead, the platelets are stimulated by the physical process of variable-speed centrifugation. No anesthesia is required for CGF therapy, and it is easy to administer. The cumulative time of releasing growth factors by CGF was only 14 days.¹⁹ Therefore, for the patient with a chronic refractory wound, repeat CGF injections may be administered within 1 to 2 weeks.

Expert consensus and treatment guidelines for vascular accidents caused by HA injection mostly stress the need to stop the HA injection and thus stop the further embolism of blood vessels by HA; inject hyaluronidase as early as possible to rapidly degenerate the HA inside and outside the blood vessels and thereby facilitate blood supply to ischemic tissues; and apply vasodilators to local blood vessels to open the collateral circulation, thus increasing the blood supply to the ischemic area.^3-5 However, angiogenesis and repair and/or regeneration of damaged tissues is largely ignored. Although various treatments and clinical studies have been published, the overall effects were unsatisfactory. The earliest possible restoration of blood supply to ischemic tissues is necessary and effective, as is accelerating the revascularization and repair/regeneration of damaged tissues.

The pathophysiologic reactions in ischemic tissues induced by vascular occlusion are opening of collateral circulation, angiectasis, and angiogenesis.²⁰ Opening of collateral circulation results in natural compensatory responses in blood vessels in normal tissues, which could bypass the occluded blood vessels. Hypoxia is an endogenous stimulatory factor that induces the generation of nitrogen monoxide, which subsequently activates angiectasis, increases the diameter of collateral vessels, reduces vascular resistance, and accelerates tissue perfusion. If the time of vascular occlusion is longer than the maximum tolerable ischemia time, ischemic tissue necrosis may occur. Necrosis induces acute inflammation and stimulates the aggregation of inflammatory cells to generate angiogenic cytokines, such as VEGF, PDGF, and bFGF. These growth factors could stimulate angiogenesis (ie, generation of vascular network surrounding the ischemic tissues that connect to the adjacent blood capillaries) and promote the restoration of blood flow to ischemic tissues.

Vascular endothelial injuries induced by the injection of HA into blood vessels could expose the subendothelial collagen and activate the typical physiologic coagulation system, such as platelets and coagulation factor XII.²¹ In addition, the injured endothelial cells release tissue factors to activate coagulation factor VIII and trigger an exogenous coagulation cascade. With the slowing of blood flow and formation of a vortex, platelets aggregate around HA and form an aggregation of white thrombi. Subsequently, the thrombus increases gradually and includes large amounts of red blood cells to form a mixed white-red thrombus. Within the first 24 hours after thrombogenesis, the HA in the vascular lumen is mixed with the visible components of blood to form a mixed thrombus. After 48 hours, the fibroblasts and endothelial cells at the vascular wall promote the growth of thrombus, which then forms granulation tissues and manifests the tissue characteristics of thrombofibrosis. Therefore, a mixed embolus is composed not only of HA but also of platelets, fibrin, and red blood cells.

The early application of hyaluronidase only dissolves HA in the embolus, while the residual components of the mixed embolus occlude blood vessels, thereby preventing the complete restoration of local blood perfusion. Typically, a skin flap can tolerate ischemia for only 8 to 13 hours.²² Thus, for cases at high risk for skin necrosis induced by HA embolism, the most critical treatment is the injection of hyaluronidase as early as possible to hydrolyze the HA and restore skin perfusion. Clinical studies have demonstrated that injection of hyaluronidase within 2 days after the occurrence of HA-related skin ischemia can prevent skin tissue necrosis.²³ If injection of hyaluronidase is delayed beyond 2 days, however, the risk of skin ischemia is increased, and full-layer skin necrosis can occur.

All patients treated in the current study reported that they had received hyaluronidase injection in outside hospitals, but the exact duration between the injection and vascular embolism was unknown. All patients transferred to the authors’ hospital exhibited different degrees of skin necrosis, and most lesions were moderate or severe. One patient was transferred to the authors’ hospital on day 2 after vascular embolism and received hyaluronidase injection and CGF therapy. Although the range of vascular embolism was large and the ischemia affected multiple areas, mild necrosis was present in most sites. Injection of HA into the artery activates the intravascular coagulation mechanisms, leading to the formation of a relatively large and insoluble embolus. Because there is no valve in facial blood vessels, the embolus could “slough off” and migrate to adjacent tissues. All patients referred to the authors’ hospital received a routine injection of hyaluronidase (dose of 400–1500 U) at the sites of ischemic wounds at the initial consultation to prevent expansion.

Vascular embolism also causes secondary ischemic damages in the blood vessel-innervated tissues. After the revascularization of some blood vessels, the damage may worsen further. Reperfusion of tissues after a period of ischemia could lead to I/R injury.²⁴ Previous treatments of vascular accidents induced by HA injection focused on the initial ischemic injuries and ignored the treatment of I/R injury. Hyaluronidase removes the embolic occlusion and improves ischemic damage, but it cannot repair tissue injuries and necrosis.

Wound healing is associated with the release of cytokines, chemokines, and growth factors in local tissues, and CGF therapy is a new clinical method for treating wounds.^15-17 The present case series demonstrated that CGF therapy in addition to hyaluronidase accelerates resolution of cyanosis and early-stage map-like discoloration of the skin, and substantially alleviates inflammation (ie, swelling, exudate). For late-stage dermal injuries, the range of blue-black changes and dark crust caused by necrosis is decreased substantially with such treatment. Additionally, the severity and duration of pain are markedly shortened. These findings demonstrate that CGF improves both the initial ischemic injuries and consequent I/R injury.

Several possible underlying mechanisms of action of CGF have been suggested, including blood vessel dilation, angiogenesis, alleviation of I/R injury, and acceleration of the repair and regeneration of injured and necrotic tissues. CGF has abundant VEGF,²⁵ and VEGF has the effect of dilating blood vessels in the skin,^9,10 which could result in opening of collateral circulation and increased blood flow to hyperperfused tissues, thereby shortening the duration of ischemia. With the removal of the occlusion in the main vessels, the revascularization by angiogenesis restores the blood flow to ischemic tissues. In ischemic and hypoxic tissues, if blood flow is not restored within the first several hours after occlusion and the maximum tolerable ischemia time is exceeded, ischemic tissue injury or necrosis can occur. This in turn induces acute inflammation,²⁰ promoting inflammatory cells to aggregate and release vascular growth factors, including PDGF, VEGF, and bFGF. PDGF is the chemokine for multiple cell types that also participates in mitosis and could activate the migration of endothelial progenitor cells to the ischemic area, thereby promoting angiogenesis.²⁶ VEGF also stimulates the migration and proliferation of vascular endothelial cells, and thus induces angiogenesis.²⁷ bFGF promotes epithelial cell proliferation and angiogenesis, regulates VEGF activity, and plays a critical role in regulating angiogenesis, cell survival, cell division, differentiation, and migration.²⁸ CGF can release various vascular growth factors, CD34-positive cells, and endothelial progenitor cell–like cells to promote angiogenesis and neovascularization through the exertion of synergistic effects in ischemic tissues within 2 to 3 days.^12,25,29 With the establishment of a distal vascular network, the ischemic tissues are connected to distal capillaries to restore blood flow to the tissues. Ischemia/reperfusion injury mainly involves the formation of oxidative free radicals, activation and infiltration of inflammatory cells, energy depletion, intracellular calcium overload, production of nitric oxide, and cell apoptosis.^30,31 Several studies have demonstrated that PRP, which contains various growth factors, alleviates I/R injuries in skin flaps by reducing the levels of ROS, inhibiting inflammatory reactions, and improving angiogenesis.^30,31 CGF also upregulates superoxide dismutase, downregulates ROS, inhibits oxidative stress, and promotes antioxidative effects,³² thereby protecting ischemic tissues from I/R injuries. CGF promotes the repair and regeneration of injured and necrotic soft tissues via cell proliferation, differentiation, migration, epithelialization, angiogenesis, and deposition of extracellular matrix to tissues via various growth factors and CD34 stem cells.^12,13,25,29

In the current case series, CGF promoted the healing of ischemic and necrotic wounds caused by facial vascular embolism following the injection of HA fillers. CGF is a nonsurgical treatment option for addressing complications of vascular embolism following dermal filler injection.

There are several limitations regarding the current study. Owing to the small sample size, this study did not include a control group to prove the efficacy of CGF in the management of skin necrosis after vascular embolization following HA injection. In addition, the majority of patients were female (n = 11), and only 1 patient was male. The effectiveness of CGF on facial vascular embolism in male patients needs further clinical verification.

The results reported herein confirmed the beneficial role of CGF in healing skin necrosis after vascular embolization caused by facial HA injection and showed that CGF can be used to accelerate the wound healing process. Together with other thrombolytic and vasodilator therapies, CGF can be used as a complementary treatment for patients with facial wounds resulting from dermal skin vascular embolism.