Peng Hu1,2, Anna Chiarini1, Jun Wu1,3, Giuliano Freddi4, Kaiyu Nie2, Ubaldo Armato1,3, Ilaria Dal Prà1,3. 1. Human Histology & Embryology Section, Department of Surgery, Dentistry, Paediatrics & Gynaecology, University of Verona Medical School, Strada Le Grazie 8, I-37134, Verona, Venetia, Italy. 2. Department of Burns & Plastic Surgery, The Affiliated Hospital of ZunYi Medical University, 149 Dalian Road, ZunYi City, 563003 Guizhou Province, China. 3. Department of Burns and Plastic Surgery, Second People's Hospital, University of Shenzhen, 3002 Sungang West Road, Futian District, Shenzhen, 518000, Guangdong Province, China. 4. Silk Biomaterials S.r.l., Via Cavour 2, I-22074, Lomazzo, Lombardy, Italy.
Abstract
BACKGROUND: Bombyx mori silk fibroin is a biomacromolecule that allows the assembly of scaffolds for tissue engineering and regeneration purposes due to its cellular adhesiveness, high biocompatibility and low immunogenicity. Earlier work showed that two types of 3D silk fibroin nonwovens (3D-SFnws) implanted into mouse subcutaneous tissue were promptly vascularized via undefined molecular mechanisms. The present study used nontumorigenic adult human dermal fibroblasts (HDFs) adhering to a third type of 3D-SFnws to assess whether HDFs release exosomes whose contents promote neoangiogenesis. METHODS: Electron microscopy imaging and physical tests defined the features of the novel carded/hydroentangled 3D-SFnws. HDFs were cultured on 3D-SFnws and polystyrene plates in an exosome-depleted medium. DNA amounts and D-glucose consumption revealed the growth and metabolic activities of HDFs on 3D-SFnws. CD9-expressing total exosome fractions were from conditioned media of 3D-SFnws and 2D polystyrene plates HDF cultures. Angiogenic growth factors (AGFs) in equal amounts of the two groups of exosomal proteins were analysed via double-antibody arrays. A tube formation assay using human dermal microvascular endothelial cells (HDMVECs) was used to evaluate the exosomes' angiogenic power. RESULTS: The novel features of the 3D-SFnws met the biomechanical requirements typical of human soft tissues. By experimental day 15, 3D-SFnws-adhering HDFs had increased 4.5-fold in numbers and metabolized 5.4-fold more D-glucose than at day 3 in vitro. Compared to polystyrene-stuck HDFs, exosomes from 3D-SFnws-adhering HDFs carried significantly higher amounts of AGFs, such as interleukin (IL)-1α, IL-4 and IL-8; angiopoietin-1 and angiopoietin-2; angiopoietin-1 receptor (or Tie-2); growth-regulated oncogene (GRO)-α, GRO-β and GRO-γ; matrix metalloproteinase-1; tissue inhibitor metalloproteinase-1; and urokinase-type plasminogen activator surface receptor, but lesser amounts of anti-angiogenic tissue inhibitor metalloproteinase-2 and pro-inflammatory monocyte chemoattractant protein-1. At concentrations from 0.62 to 10 μg/ml, the exosomes from 3D-SFnws-cultured HDFs proved their angiogenic power by inducing HDMVECs to form significant amounts of tubes in vitro. CONCLUSIONS: The structural and mechanical properties of carded/hydroentangled 3D-SFnws proved their suitability for tissue engineering and regeneration applications. Consistent with our hypothesis, 3D-SFnws-adhering HDFs released exosomes carrying several AGFs that induced HDMVECs to promptly assemble vascular tubes in vitro. Hence, we posit that once implanted in vivo, the 3D-SFnws/HDFs interactions could promote the vascularization and repair of extended skin wounds due to burns or other noxious agents in human and veterinary clinical settings.
BACKGROUND: Bombyx mori silk fibroin is a biomacromolecule that allows the assembly of scaffolds for tissue engineering and regeneration purposes due to its cellular adhesiveness, high biocompatibility and low immunogenicity. Earlier work showed that two types of 3D silk fibroin nonwovens (3D-SFnws) implanted into mouse subcutaneous tissue were promptly vascularized via undefined molecular mechanisms. The present study used nontumorigenic adult human dermal fibroblasts (HDFs) adhering to a third type of 3D-SFnws to assess whether HDFs release exosomes whose contents promote neoangiogenesis. METHODS: Electron microscopy imaging and physical tests defined the features of the novel carded/hydroentangled 3D-SFnws. HDFs were cultured on 3D-SFnws and polystyrene plates in an exosome-depleted medium. DNA amounts and D-glucose consumption revealed the growth and metabolic activities of HDFs on 3D-SFnws. CD9-expressing total exosome fractions were from conditioned media of 3D-SFnws and 2D polystyrene plates HDF cultures. Angiogenic growth factors (AGFs) in equal amounts of the two groups of exosomal proteins were analysed via double-antibody arrays. A tube formation assay using human dermal microvascular endothelial cells (HDMVECs) was used to evaluate the exosomes' angiogenic power. RESULTS: The novel features of the 3D-SFnws met the biomechanical requirements typical of human soft tissues. By experimental day 15, 3D-SFnws-adhering HDFs had increased 4.5-fold in numbers and metabolized 5.4-fold more D-glucose than at day 3 in vitro. Compared to polystyrene-stuck HDFs, exosomes from 3D-SFnws-adhering HDFs carried significantly higher amounts of AGFs, such as interleukin (IL)-1α, IL-4 and IL-8; angiopoietin-1 and angiopoietin-2; angiopoietin-1 receptor (or Tie-2); growth-regulated oncogene (GRO)-α, GRO-β and GRO-γ; matrix metalloproteinase-1; tissue inhibitor metalloproteinase-1; and urokinase-type plasminogen activator surface receptor, but lesser amounts of anti-angiogenic tissue inhibitor metalloproteinase-2 and pro-inflammatory monocyte chemoattractant protein-1. At concentrations from 0.62 to 10 μg/ml, the exosomes from 3D-SFnws-cultured HDFs proved their angiogenic power by inducing HDMVECs to form significant amounts of tubes in vitro. CONCLUSIONS: The structural and mechanical properties of carded/hydroentangled 3D-SFnws proved their suitability for tissue engineering and regeneration applications. Consistent with our hypothesis, 3D-SFnws-adhering HDFs released exosomes carrying several AGFs that induced HDMVECs to promptly assemble vascular tubes in vitro. Hence, we posit that once implanted in vivo, the 3D-SFnws/HDFs interactions could promote the vascularization and repair of extended skin wounds due to burns or other noxious agents in human and veterinary clinical settings.
Authors: J Witowski; A Thiel; R Dechend; K Dunkel; N Fouquet; T O Bender; J M Langrehr; G M Gahl; U Frei; A Jörres Journal: Am J Pathol Date: 2001-04 Impact factor: 4.307
Authors: Gregory H Altman; Frank Diaz; Caroline Jakuba; Tara Calabro; Rebecca L Horan; Jingsong Chen; Helen Lu; John Richmond; David L Kaplan Journal: Biomaterials Date: 2003-02 Impact factor: 12.479