OBJECTIVETo construct an double-layered tube-shaped poly (lactic-co-glycolic acid) (PLGA) scaffold composited with vascular endothelial growth factor (VEGF)/ platelet-derived growth factor (PDGF), and to evaluate in vivo the axial vascularization from femoral arteriovenous bundle encapsulated.

METHODSEighteen male adult New Zealand rabbits were assigned randomly into 3 groups: Experimental group (n = 8), experimental control group (n = 8), empty control group (n=2). The femoral arteriovenous bundle were separated and encapsulated in double-layered tubeshaped PLGA scaffold prepared by solution casting and particle leaching. According to the way of cell factors being composited to the prepared double-layered scaffold: 1) experimental group: VEGF in inner layer and PDGF in outer layer; 2) experimental control group: VEGF in inner layer with blank outer layer; 3) empty control group: Pure blank. Specimens were retrieved at 7, 10, 14, 21 days postoperatively (7, 10 days in empty control group). The histological evaluation was performed.

RESULTSAt 7 days postoperatively, blood vessel sprouts were observed in experimental group and experimental control group, radially from the central femoral arteriovenous bundle. At 10 days postoperatively, completely penetrations of the double-layered scaffold by abundant new generated blood vessel sprouts were observed, and density descended gradiently from inside to outside. At 14 days postoperatively, new blood vessels in experimental group showed more thickness and layered structure of the wall, while monolayer endothelial cells in experimental control group. At 21 days postoperatively, new blood vessels in experimental group showed more mature characteristics, while less density of blood vessels in experimental control group. There was no obvious blood vessel structure in empty control group.

CONCLUSIONThe double-layered tube-shaped PLGA scaffold composited with VEGF/PDGF could induce early angiogenesis.

Animals ; Lactic Acid ; Male ; Polyglycolic Acid ; Rabbits ; Tissue Engineering ; Vascular Endothelial Growth Factor A

There is increasing interest in the clinical use of flattening filter-free (FFF) beams. In this study, we aimed to investigate the dosimetric characteristics of volumetric modulated arc radiotherapy (VMAT) with FFF beams for nasopharyngeal carcinoma (NPC). Ten NPC patients were randomly selected to undergo a RapidArc plan with either FFF beams (RA-FFF) or conventional beams (RA-C). The doses to the planning target volumes (PTVs), organs at risk (OARs), and normal tissues were compared. The technical delivery parameters for RapidArc plans were also assessed to compare the characteristics of FFF and conventional beams. Both techniques delivered adequate doses to PTVs. For PTVs, RA-C delivered lower maximum and mean doses and improved conformity and homogeneity compared with RA-FFF. Both techniques provided similar maximum doses to the optic nerves and lenses. For the brain stem, spinal cord, larynx, parotid glands, oral cavity, and skin, RA-FFF showed significant dose increases compared to RA-C. The dose to normal tissue was lower in RA-FFF. The monitor units (MUs) were (536 ± 46) MU for RA-FFF and (501 ±25) MU for RA-C. The treatment duration did not significantly differ between plans. Although both treatment plans could meet clinical needs, RA-C is dosimetrically superior to RA-FFF for NPC radiotherapy.
Adult ; Aged ; Feasibility Studies ; Female ; Humans ; Male ; Middle Aged ; Nasopharyngeal Neoplasms ; pathology ; radiotherapy ; Organs at Risk ; radiation effects ; Radiometry ; methods ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; Radiotherapy, Intensity-Modulated ; methods