The role of autologous fibrin-platelet glue in plastic surgery: a preliminary report

Autologous keratinocyte suspension in platelet concentrate accelerates and enhances wound healing - a prospective randomized clinical trial on skin graft donor sites: platelet concentrate and keratinocytes on donor sites

Background

Wound healing involves complex mechanisms, which, if properly chaperoned, can enhance patient recovery. The abilities of platelets and keratinocytes may be harnessed in order to stimulate wound healing through the formation of platelet clots, the release of several growth factors and cytokines, and cell proliferation. The aim of the study was to test whether autologous keratinocyte suspensions in platelet concentrate would improve wound healing. The study was conducted at the Lausanne University Hospital, Switzerland in 45 patients, randomized to three different topical treatment groups: standard treatment serving as control, autologous platelet concentrate (PC) and keratinocytes suspended in autologous platelet concentrate (PC + K). Split thickness skin graft donor sites were chosen on the anterolateral thighs of patients undergoing plastic surgery for a variety of defects. Wound healing was assessed by the duration and quality of the healing process. Pain intensity was evaluated at day five.

Results

Healing time was reduced from 13.9 ± 0.5 days (mean ± SEM) in the control group to 7.2 ± 0.2 days in the PC group (P < 0.01). An addition of keratinocytes in suspension further reduced the healing time to 5.7 ± 0.2 days. Pain was reduced in both the PC and PC + K groups. Data showed a statistically detectable advantage of using PC + K over PC alone (P < 0.01).

Conclusion

The results demonstrate the positive contribution of autologous platelets combined with keratinocytes in stimulating wound healing and reducing pain. This strikingly simple approach could have a significant impact on patient care, especially critically burned victims for whom time is of the essence.

Clinical trial registry information

Protocol Record Identification Number: 132/03

Registry URL: http://www.clinicaltrials.gov

A novel calcium aluminate-melatonin scaffold enhances bone regeneration within a calvarial defect

Over 500,000 bone graft or bio-implant procedures are performed annually in the United States. It has been reported that osseous autograft procurement may result in donor site complications and bio-implant allografts have been associated with disease transmission. Ceramic scaffolds are only osteoconductive, limiting their clinical use. The objective of this study was to create a bone filler substitute with regenerating properties similar to natural bone. Therefore, melatonin and platelet-rich plasma (PRP) were utilized for their known osteoinductive properties. It was hypothesized that melatonin and/or PRP would enhance the osteoinductive and osteoconductive properties of calcium aluminate (CA) scaffolds to promote bone regeneration in a model of calvarial defects. The biocompatibility of CA and CA-Mel scaffolds was tested in vitro and in vivo. Data show that CA-Mel scaffolds, in comparison with CA scaffolds, enhanced the adhesion, viability, and proliferation of normal human osteoblasts cells but not that of NIH3T3 fibroblasts. Data also showed that human adult mesenchymal stem cells grown on CA or CA-Mel scaffolds showed a time-dependent induction into osteoblasts over 14days revealed through scanning electron microscopy and by alkaline phosphatase analyses. Implantation of CA-Mel scaffolds into critical size calvarial defects in female, ovariectomized rats showed that the CA-Mel scaffolds were biocompatible, allowed for tissue infiltration, and showed evidence of scaffold biodegradation by 3 and 6months. Bone regeneration, assessed using fluorochrome labeling at 3 and 6months, was greatest in animals implanted with the CA-Mel scaffold. Overall, results from this study show that CA-Mel scaffolds were osteoconductive and osteoinductive.

BLOOD-DERIVED, TISSUE ENGINEERING BIOMATERIALS

Fibrin sealant and platelet gels are human blood-derived, biodegradable, non toxic, surgical products obtained by mixing a fibrinogen concentrate or a platelet rich plasma with thrombin, respectively. Fibrin sealant is now a well known surgical tool increasingly used to stop or control bleeding, or to provide air and fluid tightness in many surgical situations. Platelet gels are newly developed preparations that are of specific interest because they contain numerous physiological growth factors and cytikines that are released upon the activation of blood platelets by thrombin. These growth factors, including PDGF, TGF-β 1, BMP, and VEGF have been shown to stimulate cell growth and differentiation with special clinical benefits for soft and bony tissue healing and regeneration. Platelet gels allow surgeons to manipulate the cellular environment of surgical sites and to guide tissue regeneration. A specific interest of such products is observed for the induction of osteogenesis and chondrogenesis. Advances in the preparation, clinical use, and safety of these two important classes of blood-derived biomaterials are reviewed.

A NOVEL TGD®DEVICE TO GENERATE THERAPEUTIC PLATELET GLUE

The surgical applications of platelet glue (a mixture of platelet gel and fibrin glue) are so far particularly prominent in plastic and orthopedic surgeries. It is shown to accelerate bone fracture and wound healing in many clinical practices. Over the years, one of the components used to prepare platelet glue (PG), thrombin, could only be obtained from pooled human plasma or bovine blood after repeated centrifugation processes. The quantity from this thrombin source is limited and its process deemed time consuming and the risk of infection does exist. Here, we present a stand alone device (TGD®, Thrombin Generation Device) which could prepare large quantities of human thrombin from autologous or single donor allogeneic plasma donations under sterile conditions. With this specific thrombin product, we could easily further mix with platelet and fibrinogen to prepare the platelet glue. PG not only contains various growth factors such as PDGF, TGF-β which are believed to be beneficial to wound healing but also increase the sticky strength in different operations. In this study, the reconstruction efficacy of PG combined with osteoconductive scaffold, biphasic calcium phosphate scaffold, for a post-operative calvarial bone defect was evaluated.

Fibrin glues of human origin

Wound healing is the response to injury and the process of tissue repair. Recent advances in cellular and molecular biology have greatly expanded our understanding of this process, which includes chemotaxis, production of matrix protein, cell replication, neovascularization and tissue remodelling. Tissue injury causes the disruption of blood vessels that is responsible for extravasation or haemorrhage of blood constituents and the first step of process in the platelet activation after exposure of collagen. Platelets initiate clotting through the coagulation system. When thrombin is formed, fibrinogen is transformed into fibrin; this is the real first step of wound healing. Fibrin glues reproduce this process and have been widely used in surgery to obtain haemostasis and expedite the process of wound healing. Immunogenicity of xenogenic products and risks of viral or prion disease transmission through commercial products have generated new interest in home-made autologous glues whose complexity was increased when platelets were added to coagulation proteins as a source of cytokines and growth factors. For the preparation of these products, the blood bankers took advantage of their usual technologies and several automated apparatuses are currently employed for the preparation of fibrinogen and thrombin concentrates. The machines for sequestration and multicomponent collection have been adapted for the concurrent procurement of plasma and platelets. A further level of complexity was introduced by the addition to glues of peripheral, bone marrow and cord-blood-derived stem cells to help or determine tissue regeneration. Instead of more new technologies, larger studies are now needed to quantify the benefits and clarify the optimal application for these products.

Cord blood (CB) stem cells for wound repair. Preliminary report of 2 cases

In 2 patients, to promote skin wound/lesion repair we used fibrin-platelet glue combined with HLA compatible (2 mismatches accepted) buffy coats containing CD 34+ cord blood cells. The fibrin platelet glue was prepared with autologous apheresis platelets and cryoprecipitate. The original product was divided into 3 and 4 aliquots respectively for a correspondent number of applications. At each application, the margins of the lesion were infiltrated with 3 ml of cord blood buffy coat, containing 30 x 10(3) CD 34+ cells. No graft versus tissue reaction was seen in our patients in a follow-up of 3-7 months. The level of improvement, scored arbitrarily from 0 to 4, was 3 and 4, respectively. Our conclusion is that the use of cord blood cells along with fibrin platelet glue is of clinical interest.

Sample preparation technique and white cell content influence the detectable levels of growth factors in platelet concentrates

BACKGROUND AND OBJECTIVES

Autologous platelet concentrate (PC) is applied locally to improve wound healing and tissue repair. Previous measurements of the growth factor content of platelets have given conflicting results. To date, there is no information on the influence of different preanalytical sample-preparation methods on the detectable amount of growth factors.

MATERIALS AND METHODS

We measured the level of growth factors in PCs obtained by plateletpheresis and by leukapheresis. We subjected aliquots of these components to six different preparation methods: freezing/thawing once or twice; dissolution in 0.5% Triton-X-100; and clot formation by the addition of calcium and thrombin with subsequent incubation for 1 h, for 24 h, or for 1 h followed by freezing and thawing.

RESULTS

In samples dissolved in Triton-X-100, higher levels of growth factors were detected than in the other specimens. In comparison to clot formation, freezing and thawing platelets twice was equivalent with respect to the release of platelet-derived growth factor (PDGF) but superior with respect to the release of transforming growth factor-beta1 (TGF-beta1). Overall, mean levels of 4.77 x 10(-16) g of PDGF-AB, 2.2 x 10(-17) g of PDGF-BB, and 2.41 x 10(-16) g of TGF-beta1 were found per single human platelet in white blood cell (WBC)-poor samples dissolved in Triton-X-100.

CONCLUSIONS

Dissolving PC in Triton-X-100 releases maximum quantities of growth factors from platelets. The release of each growth factor by any sample preparation method should be investigated and interpreted separately. The preanalytical sample-preparation method, as well as the platelet and WBC content, influence the measurable levels of growth factors in PCs. The results implicate the need to correct, considerably upwards, previous estimations of the PDGF content of platelets.