Intrinsic versus extrinsic vascularization in tissue engineering.
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Animals↗
Biomedical subjects
Elias Polykandriotis
Publications and source records attributed to Elias Polykandriotis.
Engineering of vascularized transplantable bone tissues: induction of axial vascularization in an osteoconductive matrix using an arteriovenous loop.
INTRODUCTION: Vascularization remains an obstacle to engineering of larger volume bone tissues. Our aim was to induce axial vascularization in a processed bovine cancellous bone (PBCB) matrix using an arteriovenous (AV) loop (artery, vein graft, and vein). METHODS: Custom-made PBCB discs (9 x 5 mm) were implanted into rats. In group A (n = 19), the matrices were inserted into microsurgically constructed AV loops between the femoral vessels using a vein graft from the contralateral side. In group B (n = 19), there was no vascular carrier. The matrices were encased in isolation chambers. After 2, 4, and 8 weeks, the animals were perfused with India ink via the abdominal aorta. Matrices were explanted and subjected to histological and morphometric analysis. Results were compared with intravital dynamic micro & magnetic resonance imaging and scanning electron microscopy images of vascular corrosion replicas. RESULTS: In group A, significant vascularization of the matrix had occurred by the 8th week. At this time, vascular remodeling with organization into vessels of different sizes was evident. Blood vessels originated from all 3 zones of the AV loop. Group A was significantly superior to group B in terms of vascular density and vascularization kinetics. DISCUSSION: This study demonstrates for the first time successful vascularization of solid porous matrices by means of an AV loop. Injection of osteogenic cells into axially prevascularized matrices may eventually create functional bioartificial bone tissues for reconstruction of large defects.
Animals↗
Radial collateral ligament repair of the thumb metacarpophalangeal joint using the abductor pollicis brevis tendon.
BACKGROUND: Injuries to the radial collateral ligament of the thumb metacarpophalangeal joint are less common than injuries to the ulnar side. Therefore, published data on this subject are scarce. An innovative method of radial collateral ligament repair is hereby presented, placing emphasis on the long-term results. This technically simple method was developed to allow for a biological joint stabilization based on functional and anatomical considerations. The key concept is to reestablish joint stability by spanning the tendinous portion of the insertion of the abductor pollicis brevis over the radial side of the metacarpophalangeal joint. METHODS: Nine patients with rupture of the radial collateral ligament were treated by means of the abductor pollicis brevis-plasty. All patients suffered from subacute or chronic radial ligament insufficiency. To determine the subjective results of the repair, a score was developed grading the patient's ranking of the results achieved by the abductor pollicis brevis-plasty. All patients graded the results on a scale from 1 (excellent) to 6 (unacceptable). RESULTS: Patients were operated on 37.1 +/- 14.6 days after trauma. Long-term examination was performed after 39 +/- 14.5 months. The patients showed a high satisfaction score of 1.7 +/- 0.5, with good mobility of the metacarpophalangeal I joint (range of motion, 52.2 +/- 6.7 degrees). CONCLUSION: Favorable results suggest that the abductor pollicis brevis-plasty is a suitable, safe, and technically feasible procedure for the operative treatment of chronic instability of the thumb metacarpophalangeal joint after radial hyperadduction trauma and complete rupture or deinsertion of the radial collateral ligament.
Adolescent↗
Delayed reverse sural flap for staged reconstruction of the foot and lower leg.
BACKGROUND: Soft-tissue defects of the foot and lower leg caused by traumatic injury, tumor ablation, or infection associated with osteomyelitis often require coverage by flaps. One excellent option for reconstruction of these defects is the distally based neurofasciocutaneous sural flap. It allows rapid and reliable coverage of defects from the distal third of the lower leg to the forefoot without significant functional donor-site morbidity. However, the maximal size of the flap is limited by the delicate perfusion of the arterial network associated with the superficial sensory nerve. Delay procedures may increase the reliability of large sural flaps. METHODS: The authors successfully used delayed sural flaps based on a two-step procedure for the treatment of 11 patients (three women and eight men, age 50.1 +/- 20.0 years) with osteomyelitis (n = 3), melanoma (n = 3), sarcoma (n = 1), squamous cell carcinoma (n = 1), posttraumatic defects (n = 2), and recurrent gouty ulcer (n = 1). The delay period ranged from 7 to 15 days (9.7 +/- 3.1), the length of the flap was from 9 to 19 (14.8 +/- 3.0) cm, and the width of the flap from 7 to 12 (9.2 +/- 1.3) cm. Temporary wound coverage was achieved by vacuum-assisted closure during the delay period. RESULTS: All defects were covered successfully without major complications. CONCLUSIONS: The delay procedure positively affects the viability of large sural neurofasciocutaneous flaps. The authors recommend this modification for patients with large defects at the distal third of the lower leg or foot, requiring a two-step surgical approach due to the underlying disease.
Adult↗
Interaction of exogenous liposomal insulin-like growth factor-I cDNA gene transfer with growth factors on collagen expression in acute wounds.
Growth factors have been shown to modulate the complex cascade of wound healing, however, interaction between different growth factors during dermal and epidermal regeneration is still not entirely defined. We have recently shown that exogenous liposomal gene transfer of cDNA results in physiologic expression and response in an acute wound. In the present study we determined the interaction between insulin-like growth factor-I (IGF-I), a mesenchymal growth factor, administered as liposomal cDNA, with other dermal and epidermal growth factors on collagen synthesis in an acute wound. Sprague-Dawley rats were given a scald burn to inflict an acute wound and divided into two groups to receive weekly subcutaneous injections of liposomes plus a beta-galactosidase containing plasmid (Lac Z [0.2 microg, vehicle]), or liposomes plus the IGF-I cDNA containing plasmid (2.2 microg) and Lac Z (0.2 microg). Immunological assays, histological and immunohistochemical techniques were used to determine growth factor concentration and different types of collagen (I, III, and IV) after IGF-I cDNA gene transfer. IGF-I cDNA transfer accelerated reepithelization and was associated with increased levels of IGF-I, fibroblast growth factor, keratinocyte growth factor, vascular endothelial cell growth factor, and platelet-derived growth factor protein expression. IGF-I cDNA had no effect on transforming growth factor-beta. IGF-I cDNA significantly increased type IV collagen while it had no effect on types I and III collagen. Exogenously administered IGF-I cDNA increased protein concentrations of keratinocyte growth factor, fibroblast growth factor, platelet-derived growth factor, and type IV collagen. We conclude that liposomal IGF-I gene transfer can accelerate wound healing without causing an increase in types I and III collagen expression.
Animals↗