Recombinant human platelet-derived growth factor gel speeds healing of acute full-thickness punch biopsy wounds

Recombinant human platelet-derived growth factor gel speeds healing of acute full-thickness punch biopsy wounds

Recombinant human platelet-derived growth factor gel speeds healing of acute full-thickness punch biopsy wounds Mark A. Cohen, MD, and William H. Eagl...

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Recombinant human platelet-derived growth factor gel speeds healing of acute full-thickness punch biopsy wounds Mark A. Cohen, MD, and William H. Eaglstein, MD Miami, Florida Background: Recombinant human platelet derived growth factor-BB gel (PDGF gel) has been shown to be effective in the treatment of diabetic neuropathic ulcers. It is also being used off-label to speed wound healing of flaps, grafts, and wounds from Mohs micrographic surgery. Objective: The purpose of the study was to compare the rate of healing in wounds treated with PDGF gel and with wounds treated with conventional therapy (antibiotic ointment). Methods: A double-blind controlled study of 7 healthy volunteers was performed. With a 4-mm skin punch biopsy instrument, two full-thickness wounds were made on each arm of each volunteer. Fourteen wounds treated with PDGF gel were compared with 14 wounds treated with antibiotic ointment. Healing was evaluated by visual determination of the global percentage healed and wound depth. Results: Wounds treated with PDGF gel showed a significantly faster rate of healing on each of the initial 6 follow-up visits. The greatest difference was on day 10 when PDGF-treated wounds were 71% healed compared with 28% for antibiotic-treated wounds (P = .0005). At days 22 and 24, 92.9% and 100% of the PDGF gel-treated wounds were healed, compared with 50% and 57%, respectively (P = .0313 and P = .0313), in the antibiotic ointment group. By day 29, both PDGF gel and antibiotic-treated wounds were healed. PDGF also decreased wound depth compared with wounds treated with antibiotic ointment at days 8 and 10 with P values <.0313 and <.0020, respectively. Conclusion: We conclude that PDGF gel speeds healing of acute full-thickness wounds compared with antibiotic ointment. (J Am Acad Dermatol 2001;45:857-62.)

T

he first approved topically applied growth factor approved by the Food and Drug Administration, recombinant human plateletderived growth factor-BB (rhPDGF-BB) in a sodium carboxymethylcellulose gel, Regranex (Ortho-McNeil Pharmaceutical, Raritan, NJ), has been shown to be effective in the treatment of diabetic neuropathic ulcers.1-5 It is currently under investigation for the treatment of decubitus (pressure) ulcers.6 From the Department of Dermatology and Cutaneous Surgery, University of Miami. Funding for this investigation was made possible through a grant by Ortho-McNeil Pharmaceutical, Raritan, NJ, the Takashi Aoyagi Research Fund, and the Dermatology Foundation of South Florida. Conflict of interest: None. Accepted for publication May 15, 2001. Reprint requests: William H. Eaglstein, MD, University of Miami, Department of Dermatology and Cutaneous Surgery, PO Box 016250, Miami, FL 33101. Copyright © 2001 by the American Academy of Dermatology, Inc. 0190-9622/2001/$35.00 + 0 16/1/117721 doi:10.1067/mjd.2001.117721

rhPDGF-BB is composed of 2 identical polypeptide chains linked by disulfide bonds. It is produced by the insertion of the gene for the B chain of PDGF into the yeast Saccharomyces cerevisiae.7 Its preserved, sodium carboxymethylcellulose gel does not impair wound healing and can provide a moist environment for healing.3 Although generally not appreciated, full-thickness acute wounds (ie, punch biopsy wounds) are slow to heal, often requiring more than 2 weeks before complete healing occurs. In an investigation in the healing of punch biopsy wounds, Nemeth et al8 reported that, at 1 week after wounding, none of the 21 punch biopsy wounds were healed; at 2 weeks, only 1 of 11 (7%) of the punch biopsy wounds treated with conventional therapy were healed. Although PDGF gel has been clinically established to hasten wound healing in chronic wounds (fullthickness diabetic ulcers), it is being used off-label to treat acute wounds.9 We compared a commonly used antibiotic ointment to PDGF gel on the rate of healing using acute full-thickness skin wounds. 857

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Table I. Global percentage healed Visit

PDGF gel Mean SE Antibiotic ointment Mean SE P value

8

10

15

16

22

34.28 7.61

71.07 6.82

93.00 1.24

95.83 0.78

99.85 0.53

13.21 3.17 .0078

28.21 7.64 .0005

83.35 5.54 .0488

89.08 12.90 .0371

94.92 3.51 .0313

24

100 0 95.28 2.92 .0313

29

31

36

100 0

100 0

100 0

100 0

100 0

100 0

SE, Standard error.

STUDY DESIGN After Institutional Review Board approval was obtained, a double-blind randomized controlled single-center study using healthy volunteers was conducted. Healing was evaluated on 4-mm fullthickness punch biopsy wounds treated with either PDGF gel or antibiotic ointment (Bacitracin, Fougera & Co, Melville, NY). Each patient had four 4-mm punch biopsy wounds made, 2 on each arm. Wounds on one arm were randomly assigned to be treated with PDGF gel and the wounds on the opposite arm were treated with antibiotic ointment once daily. The treated wounds were covered with an adhesive bandage. Evaluation of the wounds was conducted on days 1, 8, 10, 15, 16, 22, 24, 29, 31, and 36 (± 1 day). Study population Volunteers eligible for the study were healthy men and women age 18 years or older, willing to follow instructions and return for follow-up visits. Women of childbearing potential must have had a negative pregnancy test within 1 week of study entry and had to be using a reliable method of birth control. Volunteers were excluded if they were taking a study medication that could affect the evaluation (eg, corticosteroids). Volunteers were also excluded if they had a history of diabetes mellitus, a history of bleeding disorders or concomitant treatment with anticoagulants, a history of keloids or hypertrophic scars, or had participated in another study within 30 days. Wounding procedure Informed consent, demographic information, vital signs, medical history, and physical examination were obtained. Two sites on the inner arm of each volunteer were selected for wounding. The site to be wounded was prepared with isopropyl alcohol and anesthetized with 1 mL of 2% lidocaine with epinephrine. A 4-mm punch biopsy instrument was used to make 2 full-thickness wounds on each arm. The wounds were separat-

ed by at least 2 cm. The proximal wound on each arm was labeled “A” and the distal wound “B”. Hemostasis was obtained by means of DrySol solution (Person & Covey, Inc, Glendale, Calif), pressure, and gauze. Treatment The volunteers’ wounds were randomized to treatment by a third party not associated with the study. Each treatment regimen was random and placed into 7 envelopes numbered 1 through 7, which corresponded with a volunteer. Each wound was cleaned with saline and subsequently treated. Two wounds on one arm were treated with PDGF gel and two wounds on the other arm were treated with antibiotic ointment. During the initial and subsequent evaluations, approximately 0.1 mL of the randomly assigned medication, either PDGF gel or antibiotic ointment, was applied to the wounds by the physician performing the biopsies or by an assistant. Each wound was then covered with an adhesive bandage. The participants were given 2 syringes and a supply of bandages. Each syringe contained 5 mL of either PDGF gel or antibiotic ointment. The syringes were labeled (L) for left arm and (R) for right arm according to which arm the medication was intended for (the 2 wounds on each arm were treated with the same agent). Participants were instructed to apply an equal amount of the appropriate medication, approximately 0.1 mL, to each wound once daily and to cover with a bandage. Both medications were to be kept in the refrigerator. Efficacy evaluation At each follow-up visit, the bandages were removed and the wounds cleaned with normal saline. The primary efficacy end point was healing. A global assessment of the percentage of the wound healed was made by blinded investigators by direct visualization on each return visit. Wound depth was

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Fig 1. Mean global percentage healed. PDGF gel compared with antibiotic ointment.

Table II. Percent completely healed Visit 8

PDGF gel SE Antibiotic ointment SE P value

10

15

16

22

24

29

31

36

0/14 (0) 0/14 (0) 0/14 (0) 2/12 (16) 13/14 (92.9) 14/14 (100) 14/14 (100) 14/14 (100) 14/14 (100) 0 0 0 0.11 0.27 0 0 0 0 0/14 (0) 0/14 (0) 0/14 (0) 0/12 (0) 7/14 (50) 8/14 (57.14) 14/14 (100) 14/14 (100) 14/14 (100) 0 0 0 0 0.14 0.14 0 0 0 .5 .0313 .0313

SE, Standard error.

also clinically evaluated, on the basis of a 3-point scale (a score of 3 was assigned to full-thickness wound and a score of 1 was assigned to wounds that had no depth relative to the surrounding normal tissue upon palpation). Safety evaluation At each visit, volunteers were evaluated for the presence of pain, tenderness, swelling, erythema, edema, necrotic tissue, purulence, fibrin, and serous drainage. These parameters were evaluated as absent, mild, moderate, or marked. In addition, the volunteers were monitored for any adverse events or premature discontinuation of the medicine. Statistical methods To detect differences between the PDGF gel and antibiotic ointment groups, a Wilcoxon signed rank

test was performed. The 14 wounds treated with PDGF gel were compared with the 14 wounds treated with antibiotic ointment on each of the evaluation days. Both the global percentage healed and the depth were analyzed. Statistical analysis was carried out by means of the GraphPad In Stat program version 1.10a; 1990. Results were considered significant if the two-tailed P value was <.05.

RESULTS The study population consisted of 6 males and 1 female, ages 20 to 61. All volunteers completed the investigation. One patient missed a single evaluation on day 16. A total of 28 acute wounds (4 on each volunteer) were evaluated. The results of the global percentage healed evaluation are in Fig 1 and Table I. Compared with antibiotic ointment, there was a greater percentage of healing in the wounds treated

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Fig 2. Percentage of wounds completely healed. PDGF gel compared with antibiotic ointment.

Fig 3. Wound depth. PDGF gel compared with antibiotic ointment.

with PDGF on the initial 6 follow-up visits (days 8, 10, 15, 16, 22, and 24). None of the wounds were completely healed by day 15 (Table II). As seen in Fig 2 and Table II, 92.9% of the wounds treated with PDGF gel were healed on day 22 and 100% were healed on day 24, compared with 50% and 57% healed in the group treated with antibiotic ointment (P = .03). When analyzing the difference in the depth of the

wound, a statistically significant difference was attained on day 10 (P = .0020) (Fig 3 and Table III). In all but one volunteer, pain, tenderness, and erythema were either absent or mild. In one volunteer, moderate erythema was noted on days 15 and 16. This wound was treated with antibiotic ointment. Moderate fibrin was observed on 3 of the wounds treated with PDGF gel between days 10 and 31. One

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Table III. Depth Visit

PDGF gel Mean SE Antibiotic ointment Mean SE P value

8

10

2.5 0.14

2.07 0.07

2.93 0.07 .0313

2.78 0.11 .0020

15

16

22

24

29

31

36

1.85 0.08

1.58 1.10

1.26 0.02

1.16 0.03

1.19 0.03

1.16 0.03

1.08 0.03

1.89 0.15 .65

1.83 0.09 .0625

1.33 0.06 .4375

1.39 0.06 .0078

1.17 0.03 .75

1.19 0.03 .37

1.07 0.03 .75

SE, Standard error. 3, Full thickness; 1, even with surrounding normal skin upon palpation.

patient experienced a mild contact dermatitis from the bandage at all sites.

DISCUSSION To our knowledge, this is the first reported randomized, controlled trial of PDGF gel for the treatment of acute full-thickness human wounds. Compared with the standard of care with antibiotic ointment, PDGF gel–treated wounds healed faster and were more completely healed at all evaluations. By day 24, all of the wounds treated with PDGF gel were healed compared with only 57% of the antibiotic ointment–treated wounds. Wounds treated with antibiotic ointment were completely healed at approximately 4 weeks as opposed to 3 weeks for those treated with PDGF gel. Therefore it appears that wounds treated with PDGF gel healed nearly 25% faster than the antibiotic-treated wounds. The results of this study are consistent with earlier observations that, after 2 weeks, many punch biopsy wounds are not healed when treated with antibiotic ointment.8 We do not believe that the long time needed for full-thickness, open skin wounds to heal is generally appreciated, although the practice by some physicians of suturing punch biopsy wounds probably reflects an understanding of the need to speed healing in biopsy wounds. PDGF is one of the first growth factors found within acute wounds, being released by platelets that are also involved in hemostasis.10-12 PDGF appears to be of central importance in the wound healing cascade, being able to stimulate cell migration, cell growth, and synthesis of other growth factors.10-15 The early effect of PDGF gel seen in this study is consistent with PDGF’s release and activity early in the healing process. Its ability to speed healing of normal full-thickness wounds suggests PDGF acts pharmacologically in acute full-thickness wounds because the volunteers presumably had the normal

amount of PDGF. Although PDGF’s direct effects are known to be on cells such as fibroblasts, which are related to dermal repair, the wounds we studied had both faster dermal and epidermal repair, indicating either a direct or indirect effect of PDGF on epidermal repair. A recent study showed that PDGF-BB stimulated fibroblasts produced a diffusible growth factor, TGF-α, that acts as a keratinocyte mitogen illustrating such an indirect effect.16 In our study, the PDGF was applied daily until the wounds were healed. PDGF’s natural function seems to be in the early phase of healing. Because the PDGF-treated wounds were healing more rapidly by 8 days and were markedly “ahead” by day 10, it may be that fewer days of treatment are needed. This may have financial implications for the patient. In our region the retail price of a 15-g tube of PDGF gel currently costs approximately $430. Thus 3 weeks of therapy with 0.1 mL of PDGF gel daily for 24 days would consume approximately $68 worth of gel. However, if fewer days of treatment were needed, and if in the future the price decreases, the treatment may be more cost effective, especially should PDGF gel be packaged in smaller volumes. In studies of PDGF for diabetic ulcers, the gel was kept moist by saline gauze applied twice daily.1-5 In this study, the gel-treated wounds were covered with a bandage, which was probably not able to maintain as moist an environment. This suggests that PDGF may act quickly after application. Our findings suggest that the need to keep, or value of keeping, PDGF gel moist for a prolonged period might be questioned. Alternatively, had PDGF gel been kept moist for a longer time, its effect might have been greater. Another possibility is that, in chronic wounds, keeping PDGF gel moist is important, whereas it is unnecessary in acute wounds. Ointments in general and antibiotic ointment in particular speed healing and have become standard

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therapy among dermatologic surgeons. The finding that PDGF in a gel can stimulate healing beyond antibiotic ointment in full-thickness acute wounds suggests that the current off-label use of PDGF gel for grafts, flaps, and Mohs wounds is, indeed, helpful. Faster healing may lead to a decrease in postoperative complications such as infection and may heighten patient satisfaction. Further studies of this novel approach to wound healing are warranted. We thank Tami Araujo, MD, Alex Cazzaniga, Robert Kirsner, MD, Srdjan Prodanovich, Liliana Saap, MD, and Annie Salvarrey for their contributions to this investigation. REFERENCES 1. Steed D, Diabetic Ulcer Study Group. Clinical evaluation of recombinant human platelet-derived growth factor for the treatment of lower extremity diabetic ulcers. J Vasc Surg 1995; 21:71-81. 2. Wieman TJ, Smiell JM, Su Y. Efficacy and safety of a topical gel formulation of recombinant human platelet derived growth factor-BB (becaplermin) in patients with chronic neuropathic diabetic ulcers: a phase III randomized placebo-controlled double-blind study. Diabetes Care 1998;21:822-7. 3. D’Hemecour PA, Smiell JM, Karim MR. Sodium carboxymethylcellulose aqueous-based gel vs becaplermin gel in patients with nonhealing lower extremity diabetic ulcers.Wounds 1998; 10:69-75. 4. Wieman TJ, the Becaplermin Gel Studies Group. Clinical efficacy of becaplermin (rhPBGF-BB) gel. Am J Surg 1998;176(Suppl 2A):74-9. 5. Smiell JM, Wieman TJ, Steed DL, Perry BH, Sampson AR, Schwab BH. Efficacy and safety of becaplermin (recombinant human platelet-derived growth factor-BB) in patients with nonhealing,

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lower extremity diabetic ulcers: a combined analysis of four randomized studies. Wound Repair Regen 1999;7:335-46. Rees RS, Robson MC, Smell JM, Perry BH. Becaplermin gel in the treatment of pressure ulcers: a phase II randomized, doubleblind, placebo-controlled study. Wound Repair Regen 1999;7: 141-7. Barman JA, Noble S. Becaplermin. BioDrugs 1999;11:359-64. Nemeth AJ, Eaglstein WH,Taylor JR, Peerson LJ, Falanga V. Faster healing and less pain in skin biopsy sites treated with an occlusive dressing. Arch Dermatol 1991;127:1679-83. New product for wound healing in ulcers proves effective for dermatological surgical wounds. Skin Allergy News July 2000. Pierce GF, Mustoe TA, Altrock BW, Deuel TF, Thomason A. Role of platelet-derived growth factor in wound healing. J Cell Biochem 1991;45:319-26. Greenhalgh DG. The role of growth factors in wound healing. J Trauma 1996;41:159-67. Bennett NT, Schultz GS. Growth factors and wound healing: biochemical properties of growth factors and their receptors. Am J Surg 1993;65:728-37. Khouri RK, Koudsi B, Deune EG, Hong SP, Ozbek MR, Serdar CM, et al. Tissue generation with growth factors. Surgery 1993;114:374-80. Hill E, Turner-Beatty M, Groteweiel M, Fosha-Thomas S, Cox C, Turman C, et al. The effect of PDGF on the healing of full thickness wounds in hairless guinea pigs. Comp Biochem Physiol 1991;100A:2:365-70. Grotendorst GR, Martin GR, Pencev D, Sodek J, Harvey AK. Stimulation of granulation tissue formation by platelet-derived growth factor in normal and diabetic rats. J Clin Invest 1985;76: 2323-9. Martin B, Karmacharya, Radu A, Herlyn M, Kirschner R. Adenoviral mediated PDGF-B overexpression induces keratinocyte proliferation mediated by TGF-α. Wound Healing Society Educational Symposium. June 4-6, 2000. Toronto, Canada.

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