Fibrin scaffold

From Wikipedia, the free encyclopedia
Jump to: navigation, search

A fibrin scaffold is a network of protein that holds together and supports a variety of living tissues. It is produced naturally by the body after injury, but also can be engineered as a tissue substitute to speed healing. The scaffold consists of naturally occurring biomaterials composed of a cross-linked fibrin network and has a broad use in biomedical applications.

Fibrin consists of the blood proteins fibrinogen and thrombin which participate in blood clotting. Fibrin glue or fibrin sealant is also referred to as a fibrin based scaffold and used to control surgical bleeding, speed wound healing, seal off hollow body organs or cover holes made by standard sutures, and provide slow-release delivery of medications like antibiotics to tissues exposed.[1][2]

Fibrin scaffold use is helpful in repairing injuries to the urinary tract,[3] liver[4] lung,[5] spleen,[6] kidney,[7] and heart.[8] In biomedical research, fibrin scaffolds have been used to fill bone cavities, repair neurons, heart valves,[9] vascular grafts[10] and the surface of the eye.

The complexity of biological systems requires customized care to sustain their function. When they are no longer able to perform their purpose, interference of new cells and biological cues is provided by a scaffold material. Fibrin scaffold has many aspects like being biocompatible, biodegradable and easily processable. Furthermore, it has an autologous nature and it can be manipulated in various size and shape. Inherent role in wound healing is helpful in surgical applications. Many factors can be bound to fibrin scaffold and those can be released in a cell-controlled manner. Its stiffness can be managed by changing the concentration according to needs of surrounding or encapsulated cells. Additional mechanical properties can be obtained by combining fibrin with other suitable scaffolds. Each biomedical application has its own characteristic requirement for different kinds of tissues and recent studies with fibrin scaffold are promising towards faster recovery, less complications and long-lasting solutions.

Advantages of fibrin scaffold[edit]

Fibrin scaffold is an important element in tissue engineering approaches as a scaffold material. It is advantageous opposed to synthetic polymers and collagen gels when cost, inflammation, immune response, toxicity and cell adhesion are concerned.[11] When there is a trauma in body, cells at site start the cascade of blood clotting and fibrin is the first scaffold formed normally.[12] To achieve in clinical use of a scaffold, fast and entire incorporation into host tissue is very essential.[13] Regeneration of the tissue and the degradation of the scaffold should be balanced in terms of rate, surface area and interaction so that ideal templating can be achieved.[14] Fibrin satisfies many requirements of scaffold functions. Biomaterials made up of fibrin can attach many biological surfaces with high adhesion. Its biocompatibility comes from being not toxic, allergenic or inflammatory.[14][15][16] By the help of fibrinolysis inhibitors[17] or fiber cross-linkers, biodegradation can be managed.[16][18] Fibrin can be provided from individuals to be treated many times so that gels from autologous fibrin have no undesired immunogenic reactions in addition to be reproducible.[14][19][20] Inherently, structure and biochemistry of fibrin has an important role in wound healing.[21] Although there are limitations due to diffusion, exceptional cellular growth and tissue development can be achieved.[14][22] According to the application, fibrin scaffold characteristics can be adjustable by manipulating concentrations of components. Long-lasting durable fibrin hydrogels are enviable in many applications.[21][23][24]

Fibrin gel formation and enrichment[edit]

Polymerization time of fibrinogen and thrombin is affected primarily by concentration of thrombin and temperature, while fibrinogen concentration has a minor effect. Fibrin gel characterization by scanning electron microscopy reveals that thick fibers make up a dense structure at lower fibrinogen concentrations (5 mg/ml) and thinner fibers and looser gel can be obtained as fibrinogen concentration (20 mg/ml) increases whereas increase in thrombin concentration (from 0.5 U/ml to 5 U/ml) has no such significant result although the fibers steadily get thinner.[25]

Fibrin gels can be enriched by addition of other extracellular matrix (ECM) components such as fibronectin, vitronectin, laminin and collagen. These can be linked covalently to fibrin scaffold by reactions catalyzed by transglutaminase.[26] Laminin originated substrate amino acid sequences for transglutaminase can be IKVAV, YIGSR or RNIAEIIKDI. Collagen originated sequence is DGEA and many other ECM protein originated RGD sequence can be given as other examples.[26][27] Heparin binding sequences KβAFAKLAARLYRKA, RβAFARLAARLYRRA, KHKGRDVILKKDVR, YKKIIKKL are from antithrombin III, modified antithrombin III, neural cell adhesion molecule and platelet factor 4, respectively. Heparin-binding growth factors can be attached to heparin binding domains via heparin. As a result, a reservoir can be provided instead of passive diffusion by liberation of growth factors in extended time.[28][29] Acidic and basic fibroblast growth factor, neurotrophin 3, transforming growth factor beta 1, transforming growth factor beta 2, nerve growth factor, brain derived neurotrophic factor can be given as examples for such growth factors.[18][28][29][30][31][32]


For some tissues like cartilage, highly dense polymeric scaffolds such as polyethylene glycol (PEG) are essential due to mechanical stress and that can be achieved by combining them with natural biodegradable cell-adhesive scaffolds since cells can not attach to synthetic polymers and take proper signals for normal cell function. Various scaffold combinations with PEG-based hydrogels are studied to assess the chondrogenic response to dynamic strain stimulation in a recent study. PEG-Proteoglycan, PEG-Fibrinogen, PEG-Albumin conjugates and only PEG including hydrogels are used to evaluate the mechanical effect on bovine chondrocytes by using a pneumatic reactor system. The most substantial increase in stiffness is observed in PEG-Fibrinogen conjugated hydrogel after 28 days of mechanical stimulation.[33]


Use in tissue engineering[edit]

Bone tissue[edit]

In orthopedics, methods with minimum invasion are desired and improving injectable systems is a leading aim. Bone cavities can be filled by polymerizing materials when injected and adaptation to the shape of the cavity can be provided. Shorter surgical operation time, minimum large muscle retaraction harm, smaller scar size, less pain after operation and consequently faster recovery can be obtained by using such systems.[15] In a study to evaluate if injectable fibrin scaffold is helpful for transplantation of bone marrow stromal cell (BMSC) when central nervous system (CNS) tissue is damaged, Yasuda et al. found that BMSC has extended survival, migration and differentiation after transplantation to rat cortical lesion although there is complete degradation of fibrin matrix after four weeks.[34] Another study to assess if fibrin glue enriched with platelet is better than just platelet rich plasma (PRP) on bone formation was conducted. Each combined with bone marrow mesenchymal stem cells and bone morphogenetic protein 2 (BMP-2) are injected into the subcutaneous space. Results shows that fibrin glue enriched with platelet has better osteogenic properties when compared to PRP.[35] To initiate and speed up tissue repair and regeneration, platelet-rich fibrin gels are ideal since they have a high concentration of platelet releasing growth factors and bioactive proteins.[36] Addition of fibrin glue to calcium phosphate granules has promising results leading to faster bone repair by inducing mineralization and possible effects of fibrin on angiogenesis, cell attachment and proliferation.[37]

Cardiac tissue[edit]

Valvular heart disease is a major cause of death globally. Both mechanical valves and fixed biological xenograft or homografts used clinically have many drawbacks.[38] One study focused on fibrin-based heart valves to assess structure and mechanical durability on sheep revealed promising potential for patient originated valve replacements. From autologous arterial-derived cells and fibrin scaffold, tissue engineered heart valves are formed, then mechanically conditioned and transplanted into the pulmonary trunk of the same animals. The preliminary result are potentially hopeful towards autologous heart valve production.[39]

Vascular graft[edit]

In atherosclerosis, a severe disease in modern society, coronary blood vessels occlude. These vessels have to be freed and held open i.e. by stents. Unfortunately after certain time these vessels close again and have to be bypassed to allow for upkeep of circulation. Usually autologous vessels from the patient or synthetic polymer grafts are used for this purpose. Both options have disadvantages. Firstly there are only few autologous vessels available in a human body that might be of low quality, considering the health status of the patient. The synthetic polymer based grafts on the other hand often have insufficient haemocompatibility and thus rapidly occlude - a problem that is especially prone in small calibre grafts. In this context the fibrin gel based tissue engineering of autologous vessel substitutes is a very promising approach to overcome the current problems. Cells and fibrin are isolated by low invasive procedure from the patient and shaped in individual moulds to meet the required dimensions. Additional pre-cultivation in a specialized bioreactor[40] is inevitable to ensure appropriate properties of the graft.[41][42][43]

Ocular tissue[edit]

Bullous keratopathy that is characterized by corneal stromal edema related to cell loss and endothelial decompensation as well as subepithelial fibrosis and corneal vascularization in further cases, results vision problems due to loss of corneal transparency.[44] Fibrin glue is used as a sutureless method onto the corneal surface to fix amniotic membrane that is cryopreserved. Complete re-epithelialization on the ocular surface with no symptom is achieved in 3 weeks. Results show that fibrin glue fixation is easy, reliable and efficient with the corneal surface.[45]

Nervous tissue[edit]

Because fibrin fulfills the mechanical aspects of neuronal growth without initiation of glial proliferation, it can be potentially used in neuronal wound healing even with no need of growth factors or such constituents.[12] Neurons and astrocytes, two major cell type of central nervous system, can show various responses to differences in matrix stiffness.[46] Neuronal development of precursor cells is maintained by gels with low elastic modulus.[47] When stiffness of the matrix is more than that of a normal brain, extension of spinal cord and cortical brain neurons is inhibited since neurite extension and branch forming take place on soft materials (<1000Pa). In a study, fibrins from different species are used to compare the effects on neurite growth of mouse spinal cord neurons. Among salmon, bovine and human fibrin in addition to Matrigel(R), salmon fibrin promotes the neurite growth best and it is more proteolysis resistant than mammalian fibrins. Because down to 0 °C, salmon fibrinogen can clot whereas polymerization of human fibrinogen occurs slowly below 37 °C, this can be taken as an advantage in surgical settings that are cooler. Therefore, for treatment of central nervous system damages, salmon fibrin can be a useful biomaterial.[12][48]


For sciatic nerve regeneration, fibrin scaffold is used with glial derived neurotrophic factor (GDNF) in a recent study. Survival of both sensory and motor neurons is promoted by glial-derived neurotrophic factor and its delivery to peripheral nervous system improves regeneration after an injury. GDNF and nerve growth factor (NGF) is sequestered in the gel via a bi-domain peptide. This peptide is composed of heparin binding domain and transglutaminase substrate domain which can be cross-linked into the fibrin matrix by polymerization via transglutaminase activity of factor XIIIa. Many neurotrophic factors can bind to heparin through its sulfated domains. This is the affinity-based delivery system in which growth factors are released by cell-based degradation control. After a 13 mm rat sciatic nerve defect is made, the fibrin matrix delivery system is applied to the gap as a nerve guiding channel. Results show that such a delivery system is efficient to enhance maturity and promote organized architecture of nerve regenerating in presence of GDNF, in addition to expressing the promising treatment variations for peripheral nerve injuries.[49]


Use in gene delivery[edit]

The use of fibrin hydrogel in gene delivery (transfection) is studied to address essential factors controlling the delivery process such as fibrinogen and pDNA concentration in addition to significance of cell-mediated fibrin degradation for pursuing the potential of cell-transfection microarray engineering or in vivo gene transfer. Gene transfer is more successful in-gel than on-gel probably because of proximity of lipoplexes and target cells. Less cytotoxicity is observed due to less use of transfection agents like lipofectamine and steady degradation of fibrin. Consequently, each cell type requires optimization of fibrinogen and pDNA concentrations for higher transfection yields and studies towards high-throughput transfection microarray experiments are promising.[50]

References[edit]

  1. ^ Fibrin Sealants - test, blood, complications, time, infection, risk, rate, Definition, Purpose, Description, Preparation, Normal results
  2. ^ Atrah HI (April 1994). "Fibrin glue". BMJ 308 (6934): 933–4. doi:10.1136/bmj.308.6934.933. PMC 2539755. PMID 8173397. 
  3. ^ Evans LA, Ferguson KH, Foley JP, Rozanski TA, Morey AF (April 2003). "Fibrin sealant for the management of genitourinary injuries, fistulas and surgical complications". The Journal of Urology 169 (4): 1360–2. doi:10.1097/01.ju.0000052663.84060.ea. PMID 12629361. 
  4. ^ Feinstein AJ, Varela JE, Cohn SM, Compton RP, McKenney MG (2001). "Fibrin glue eliminates the need for packing after complex liver injuries". Yale Journal of Biology and Medicine 74 (5): 315–21. PMC 2588746. PMID 11769337. 
  5. ^ Bastarache JA (March 2009). "The complex role of fibrin in acute lung injury". American Journal of Physiology. Lung Cellular and Molecular Physiology 296 (3): L275–6. doi:10.1152/ajplung.90633.2008. PMID 19118088. 
  6. ^ Modi P, Rahamim J (July 2005). "Fibrin sealant treatment of splenic injuries during oesophagectomy". European Journal of Cardio-thoracic Surgery 28 (1): 167–8. doi:10.1016/j.ejcts.2005.02.045. PMID 15876541. 
  7. ^ Patel R, Caruso RP, Taneja S, Stifelman M (November 2003). "Use of fibrin glue and gelfoam to repair collecting system injuries in a porcine model: implications for the technique of laparoscopic partial nephrectomy". Journal of Endourology 17 (9): 799–804. doi:10.1089/089277903770802416. PMID 14642047. 
  8. ^ Toda K, Yoshitatsu M, Izutani H, Ihara K (August 2007). "Surgical management of penetrating cardiac injuries using a fibrin glue sheet". Interactive Cardiovascular and Thoracic Surgery 6 (4): 577–8. doi:10.1510/icvts.2007.156372. PMID 17669945. 
  9. ^ "AME: Heart Valves". www.ame.hia.rwth-aachen.de. Retrieved 2010-05-31. 
  10. ^ "AME: Vascular Grafts". www.ame.hia.rwth-aachen.de. Retrieved 2010-05-31. 
  11. ^ Ahmed TA, Dare EV, Hincke M (June 2008). "Fibrin: a versatile scaffold for tissue engineering applications". Tissue Engineering. Part B, Reviews 14 (2): 199–215. doi:10.1089/ten.teb.2007.0435. PMID 18544016. 
  12. ^ a b c Uibo R, Laidmäe I, Sawyer ES, et al. (May 2009). "Soft materials to treat central nervous system injuries: evaluation of the suitability of non-mammalian fibrin gels". Biochimica et Biophysica Acta 1793 (5): 924–30. doi:10.1016/j.bbamcr.2009.01.007. PMC 2895977. PMID 19344675. 
  13. ^ Shaikh FM, Callanan A, Kavanagh EG, Burke PE, Grace PA, McGloughlin TM (2008). "Fibrin: a natural biodegradable scaffold in vascular tissue engineering". Cells, Tissues, Organs 188 (4): 333–46. doi:10.1159/000139772. PMID 18552484. 
  14. ^ a b c d Ye Q, Zünd G, Benedikt P, et al. (May 2000). "Fibrin gel as a three dimensional matrix in cardiovascular tissue engineering". European Journal of Cardio-thoracic Surgery 17 (5): 587–91. doi:10.1016/S1010-7940(00)00373-0. PMID 10814924. 
  15. ^ a b Bensaïd W, Triffitt JT, Blanchat C, Oudina K, Sedel L, Petite H (June 2003). "A biodegradable fibrin scaffold for mesenchymal stem cell transplantation". Biomaterials 24 (14): 2497–502. doi:10.1016/S0142-9612(02)00618-X. PMID 12695076. 
  16. ^ a b Wozniak G (August 2003). "Fibrin sealants in supporting surgical techniques: The importance of individual components". Cardiovascular Surgery 11 (Suppl 1): 17–21. doi:10.1016/S0967-2109(03)00067-X. PMID 12869984. 
  17. ^ Cholewinski E, Dietrich M, Flanagan TC, Schmitz-Rode T, Jockenhoevel S (November 2009). "Tranexamic acid--an alternative to aprotinin in fibrin-based cardiovascular tissue engineering". Tissue Engineering. Part a 15 (11): 3645–53. doi:10.1089/ten.TEA.2009.0235. PMID 19496679. 
  18. ^ a b Mol A, van Lieshout MI, Dam-de Veen CG, et al. (June 2005). "Fibrin as a cell carrier in cardiovascular tissue engineering applications". Biomaterials 26 (16): 3113–21. doi:10.1016/j.biomaterials.2004.08.007. PMID 15603806. 
  19. ^ Aper T, Schmidt A, Duchrow M, Bruch HP (January 2007). "Autologous blood vessels engineered from peripheral blood sample". European Journal of Vascular and Endovascular Surgery 33 (1): 33–9. doi:10.1016/j.ejvs.2006.08.008. PMID 17070080. 
  20. ^ Jockenhoevel S, Chalabi K, Sachweh JS, et al. (October 2001). "Tissue engineering: complete autologous valve conduit--a new moulding technique". The Thoracic and Cardiovascular Surgeon 49 (5): 287–90. doi:10.1055/s-2001-17807. PMID 11605139. 
  21. ^ a b Rowe SL, Lee S, Stegemann JP (January 2007). "Influence of thrombin concentration on the mechanical and morphological properties of cell-seeded fibrin hydrogels". Acta Biomaterialia 3 (1): 59–67. doi:10.1016/j.actbio.2006.08.006. PMC 1852453. PMID 17085089. 
  22. ^ Aper T, Teebken OE, Steinhoff G, Haverich A (September 2004). "Use of a fibrin preparation in the engineering of a vascular graft model". European Journal of Vascular and Endovascular Surgery 28 (3): 296–302. doi:10.1016/j.ejvs.2004.05.016. PMID 15288634. 
  23. ^ Eyrich D, Brandl F, Appel B, et al. (January 2007). "Long-term stable fibrin gels for cartilage engineering". Biomaterials 28 (1): 55–65. doi:10.1016/j.biomaterials.2006.08.027. PMID 16962167. 
  24. ^ Kjaergard HK, Weis-Fogh US (1994). "Important factors influencing the strength of autologous fibrin glue; the fibrin concentration and reaction time--comparison of strength with commercial fibrin glue". European Surgical Research 26 (5): 273–6. doi:10.1159/000129346. PMID 7835384. 
  25. ^ Zhao H, Ma L, Zhou J, Mao Z, Gao C, Shen J (March 2008). "Fabrication and physical and biological properties of fibrin gel derived from human plasma". Biomedical Materials 3 (1): 015001. doi:10.1088/1748-6041/3/1/015001. PMID 18458488. 
  26. ^ a b Schense JC, Hubbell JA (1999). "Cross-linking exogenous bifunctional peptides into fibrin gels with factor XIIIa". Bioconjugate Chemistry 10 (1): 75–81. doi:10.1021/bc9800769. PMID 9893967. 
  27. ^ Schense JC, Bloch J, Aebischer P, Hubbell JA (April 2000). "Enzymatic incorporation of bioactive peptides into fibrin matrices enhances neurite extension". Nature Biotechnology 18 (4): 415–9. doi:10.1038/74473. PMID 10748522. 
  28. ^ a b Sakiyama-Elbert SE, Hubbell JA (April 2000). "Development of fibrin derivatives for controlled release of heparin-binding growth factors". Journal of Controlled Release 65 (3): 389–402. doi:10.1016/S0168-3659(99)00221-7. PMID 10699297. 
  29. ^ a b Lee, A.C., et al., Experimental Neurology, 2003. 184(1): p. 295-303.
  30. ^ Taylor SJ, McDonald JW, Sakiyama-Elbert SE (August 2004). "Controlled release of neurotrophin-3 from fibrin gels for spinal cord injury". Journal of Controlled Release 98 (2): 281–94. doi:10.1016/j.jconrel.2004.05.003. PMID 15262419. 
  31. ^ Sakiyama-Elbert SE, Hubbell JA (October 2000). "Controlled release of nerve growth factor from a heparin-containing fibrin-based cell ingrowth matrix". Journal of Controlled Release 69 (1): 149–58. doi:10.1016/S0168-3659(00)00296-0. PMID 11018553. 
  32. ^ Lyon M, Rushton G, Gallagher JT (July 1997). "The interaction of the transforming growth factor-betas with heparin/heparan sulfate is isoform-specific". The Journal of Biological Chemistry 272 (29): 18000–6. doi:10.1074/jbc.272.29.18000. PMID 9218427. 
  33. ^ Appelman TP, Mizrahi J, Elisseeff JH, Seliktar D (February 2009). "The differential effect of scaffold composition and architecture on chondrocyte response to mechanical stimulation". Biomaterials 30 (4): 518–25. doi:10.1016/j.biomaterials.2008.09.063. PMID 19000634. 
  34. ^ Yasuda H, Kuroda S, Shichinohe H, Kamei S, Kawamura R, Iwasaki Y (February 2010). "Effect of biodegradable fibrin scaffold on survival, migration, and differentiation of transplanted bone marrow stromal cells after cortical injury in rats". Journal of Neurosurgery 112 (2): 336–44. doi:10.3171/2009.2.JNS08495. PMID 19267524. 
  35. ^ Zhu SJ, Choi BH, Huh JY, Jung JH, Kim BY, Lee SH (February 2006). "A comparative qualitative histological analysis of tissue-engineered bone using bone marrow mesenchymal stem cells, alveolar bone cells, and periosteal cells". Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics 101 (2): 164–9. doi:10.1016/j.tripleo.2005.04.006. PMID 16448916. 
  36. ^ Altmeppen J, Hansen E, Bonnländer GL, Horch RE, Jeschke MG (April 2004). "Composition and characteristics of an autologous thrombocyte gel". The Journal of Surgical Research 117 (2): 202–7. doi:10.1016/j.jss.2003.10.019. PMID 15047124. 
  37. ^ Le Nihouannen D, Guehennec LL, Rouillon T, et al. (May 2006). "Micro-architecture of calcium phosphate granules and fibrin glue composites for bone tissue engineering". Biomaterials 27 (13): 2716–22. doi:10.1016/j.biomaterials.2005.11.038. PMID 16378638. 
  38. ^ Schmidt D, Hoerstrup SP (September 2006). "Tissue engineered heart valves based on human cells". Swiss Medical Weekly 136 (39-40): 618–23. PMID 17086507. 
  39. ^ Flanagan TC, Sachweh JS, Frese J, et al. (October 2009). "In vivo remodeling and structural characterization of fibrin-based tissue-engineered heart valves in the adult sheep model". Tissue Engineering. Part a 15 (10): 2965–76. doi:10.1089/ten.TEA.2009.0018. PMID 19320544. 
  40. ^ AME: Bioreactor Technologies
  41. ^ Tschoeke B, Flanagan TC, Koch S, et al. (August 2009). "Tissue-engineered small-caliber vascular graft based on a novel biodegradable composite fibrin-polylactide scaffold". Tissue Engineering. Part a 15 (8): 1909–18. doi:10.1089/ten.tea.2008.0499. PMID 19125650. 
  42. ^ Flanagan TC, Tschoeke B, Diamantouros S, Schmitz-Rode T, Jockenhoevel S (February 2009). "Mechanical properties of tissue-engineered vascular grafts: response to letter to the editor". Artificial Organs 33 (2): 194–6. doi:10.1111/j.1525-1594.2008.00708.x. PMID 19178467. 
  43. ^ Koch S, Flanagan TC, Sachweh JS, et al. (June 2010). "Fibrin-polylactide-based tissue-engineered vascular graft in the arterial circulation". Biomaterials 31 (17): 4731–9. doi:10.1016/j.biomaterials.2010.02.051. PMID 20304484. 
  44. ^ Gonçalves ED, Campos M, Paris F, Gomes JA, Farias CC (2008). "Ceratopatia bolhosa: etiopatogênese e tratamento" [Bullous keratopathy: etiopathogenesis and treatment]. Arquivos Brasileiros de Oftalmologia (in Portuguese) 71 (6 Suppl): 61–4. doi:10.1590/S0004-27492008000700012. PMID 19274413. 
  45. ^ Chawla B, Tandon R (2008). "Sutureless amniotic membrane fixation with fibrin glue in symptomatic bullous keratopathy with poor visual potential". European Journal of Ophthalmology 18 (6): 998–1001. PMID 18988175. 
  46. ^ Georges PC, Miller WJ, Meaney DF, Sawyer ES, Janmey PA (April 2006). "Matrices with compliance comparable to that of brain tissue select neuronal over glial growth in mixed cortical cultures". Biophysical Journal 90 (8): 3012–8. doi:10.1529/biophysj.105.073114. PMC 1414567. PMID 16461391. 
  47. ^ Saha K, Keung AJ, Irwin EF, et al. (November 2008). "Substrate modulus directs neural stem cell behavior". Biophysical Journal 95 (9): 4426–38. doi:10.1529/biophysj.108.132217. PMC 2567955. PMID 18658232. 
  48. ^ Ju YE, Janmey PA, McCormick ME, Sawyer ES, Flanagan LA (April 2007). "Enhanced neurite growth from mammalian neurons in three-dimensional salmon fibrin gels". Biomaterials 28 (12): 2097–108. doi:10.1016/j.biomaterials.2007.01.008. PMC 1991290. PMID 17258313. 
  49. ^ Wood MD, Moore AM, Hunter DA, et al. (May 2009). "Affinity-based release of glial-derived neurotrophic factor from fibrin matrices enhances sciatic nerve regeneration". Acta Biomaterialia 5 (4): 959–68. doi:10.1016/j.actbio.2008.11.008. PMC 2678870. PMID 19103514. 
  50. ^ Lei P, Padmashali RM, Andreadis ST (August 2009). "Cell-controlled and spatially arrayed gene delivery from fibrin hydrogels". Biomaterials 30 (22): 3790–9. doi:10.1016/j.biomaterials.2009.03.049. PMC 2692826. PMID 19395019.