Mathias Wilhelmi

Laser Fabrication of 3D Gelatin Scaffolds for the Generation of Bioartificial Tissues

In the present work, the two-photon polymerization (2PP) technique was applied to develop precisely defined biodegradable 3D tissue engineering scaffolds. The scaffolds were fabricated via photopolymerization of gelatin modified with methacrylamide moieties. The results indicate that the gelatin derivative (GelMod) preserves its enzymatic degradation capability after photopolymerization. In addition, the developed scaffolds using 2PP support primary adipose-derived stem cell (ASC) adhesion, proliferation and differentiation into the anticipated lineage.

In vivo repopulation of xenogeneic and allogeneic acellular valve matrix conduits in the pulmonary circulation

BACKGROUND Approaches to in vivo repopulation of acellularized valve matrix constructs have been described recently. However, early calcification of acellularized matrices repopulated in vivo remains a major obstacle. We hypothesised that the matrix composition has a significant influence on the onset of early calcification. Therefore, we evaluated the calcification of acellularized allogenic ovine (AVMC) and xenogenic porcine (XVMC) valve matrix conduits in the pulmonary circulation in a sheep model. METHODS Porcine (n = 3) and sheep (n = 3) pulmonary valve conduits were acellularized by trypsin/EDTA digestion and then implanted into healthy sheep in pulmonary valve position using extracorporeal bypass support. Transthoracic echocardiography (TTE) was performed at 12 and 24 weeks after the implantation. The animals were sacrificed at week 24 or earlier when severe calcification of the valve conduit became evident by TTE. The valves were examined histologically and biochemically. RESULTS All AVMC revealed severe calcification after 12 weeks with focal endothelial cell clustering and no interstitial valve tissue reconstitution. In contrast, after 24 weeks XVMC indicated mild calcification on histologic examination (von Kossa staining) with histologic reconstitution of valve tissue and confluent endothelial surface coverage. Furthermore, immunohistologic analysis revealed reconstitution of surface endothelial cell monolayer (von Willebrand factor), and interstitial myofibroblasts (Vimentin/Desmin). CONCLUSIONS Porcine acellularized XVMC are resistant to early calcification during in vivo reseeding. Furthermore, XVMC are repopulated in vivo with valve-specific cell types within 24 weeks resembling native valve tissue.

Eight-year experience with cryopreserved arterial homografts for the in situ reconstruction of abdominal aortic infections

OBJECTIVE This study investigated short-term and long-term outcomes in patients with abdominal aortic infection (mycotic aneurysm, prosthetic graft infection, aortoenteric fistula) managed by total excision of the aneurysm or the infected vascular graft and in situ aortic reconstruction with a cryopreserved arterial homograft (CAH). METHODS From January 2000 to December 2008, 110 consecutive patients underwent CAH implantation for treatment of vascular infections. In 57 (52%), in situ revascularization of the abdominal aorta with Y-prosthesis constructed from CAHs was performed. Early outcome included 30-day mortality and the levels of daily blood markers (leucocytes, C-reactive protein, and platelets) during the postsurgical 10-day period. We reported long-term survival and freedom from reoperation rates, including all indications for reoperation. RESULTS Indications for operation were infected vascular graft in 31 patients (55%), aortodigestive fistulae in 11 (19%), nonruptured mycotic aneurysms in 4 (7%), and ruptured mycotic aneurysms of abdominal aorta in 11 (19%). In 39 of 57 patients (68%), the intraoperative specimens were positive for at least one microorganism, and Staphylococcus aureus was present in 14 (25%). In 32 patients (82%) with intraoperative specimens positive for microorganisms, there was no evidence of the intraoperatively detected microorganisms in the postoperative specimens (wound, blood culture, and drainage fluid). The peak value of leucocytes (13.7 +/- 4.4 x 10(3)/L) and C-reactive protein (200 +/- 75 mg/L) occurred on postoperative day 3. Platelets reached the lowest value on postoperative day 2 (178 +/- 67 x 10(9)/L). Median peak body temperature was 37.7 degrees +/- 0.6 degrees C. Thirty-day mortality was 9% (5 of 57 patients). Median follow-up was 36 months (range, 4-118 months); 3-year survival was 81%, and freedom from reoperation was 89%. Five patients (9%) required reoperation, in one patient each for postoperative bleeding, acute cholecystitis, homograft occlusion, homograft-duodenum fistula, and aneurysmal degeneration. No recurrence of infection was reported. CONCLUSION These results demonstrate an encouraging outcome after cryopreserved allograft implantation for the treatment of vascular infections in the abdominal aorta. The data represent a basis for future comparisons with other treatment modalities for vascular infections, including silver-coated prostheses and autogenous femoral veins.

Cryopreserved arterial homografts vs silver-coated Dacron grafts for abdominal aortic infections with intraoperative evidence of microorganisms

OBJECTIVE The gold standard for the treatment of abdominal aortic infections remains controversial. Cryopreserved arterial homografts and silver-coated Dacron grafts have both been advocated as reasonable grafts. Direct clinical or experimental comparisons between these two treatment options have not been published before. This study compared cryopreserved arterial homografts and silver-coated Dacron grafts for the treatment of abdominal aortic infections in a contaminated intraoperative field. METHODS From January 2004 to December 2009, 56 patients underwent in situ arterial reconstruction for an abdominal aortic infection. Patients with negative intraoperative microbiologic specimens were excluded. We compared 22 of 36 patients (61%) receiving cryopreserved arterial homografts (group A) vs 11 of 20 (55%) receiving a silver-coated Dacron graft (group B). Primary outcomes were survival and limb salvage; secondary outcomes were graft patency and reinfection. Direct costs of therapy were also calculated. RESULTS Thirty-day mortality was 14% in group A and 18% in group B (P >.99), and 2-year survival rates were 82% and 73%, respectively (P = .79). After 2 years, limb salvage was 96% and 100%, respectively (P = .50), whereas graft patency was 100% for both groups. Major complications were an aneurysmal degeneration in group A and graft reinfection in group B (n = 2). Median direct costs of therapy (in US

The effect of detergent-based decellularization procedures on cellular proteins and immunogenicity in equine carotid artery grafts

) were

The Role of Pericyte Detachment in Vascular Rarefaction

41,697 (range,

LMNA Mutations in Cardiac Transplant Recipients

28,347-

The role of cerebrospinal fluid S100 and lactate to predict clinically evident spinal cord ischaemia in thoraco-abdominal aortic surgery.

53,362) in group A and

Heart transplantation: echocardiographic assessment of morphology and function after more than 10 years of follow-up

15,531 (range,

Massive Postoperative Rhabdomyolysis Following Combined CABG/Abdominal Aortic Replacement: A Possible Association With HMG-CoA Reductase Inhibitors

11,310-