Impact of local delivery of allogeneic chondrocytes on the biological response and healing of the sternum bones after sternotomy.

Median sternotomy is the surgical method of choice for many procedures where one of the main problems is the long post-operative wound healing process leading to sternal dehiscence and the development of infection. This leads to prolonged hospital stay and increased mortality due to post-operative complications. A promising solution seems to be the use of allogeneic chondrocytes for wound treatment, whose properties in the field of cartilage reconstruction are widely used in medicine, mainly in orthopedics. In the present study, we investigated the effect of local delivery of allogeneic chondrocytes on the biological response and healing of the sternum after sternotomy. We optimized the culture conditions for the isolated chondrocytes, which were then applied to the sternal incision wound. Chondrocytes in the culture were assessed on the basis of the presence of chondrocyte-specific genes: Sox9, Aggrecan and Collagen II. In turn, the histopathological and immunohistochemical evaluation was used to assess the safety of implantation. In our work, we demonstrated the possibility of obtaining a viable culture of chondrocytes, which were successfully introduced into the sternal wound after sternotomy. Importantly, implantation of allogeneic chondrocytes showed no significant side effects. The obtained results open new possibilities for research on the use of allogeneic chondrocytes in the process of accelerating wound healing after median sternotomy.

Nanospheres encapsulated everolimus delivery into arterial wall-the tissue pharmacokinetics and vascular response experimental study.

OBJECTIVE: This study aimed to evaluate the pharmacokinetic profile and tissue effects of everolimus delivered into arterial wall using biodegradable nanospheres. BACKGROUND: Delivery of everolimus into the arterial wall is challenging due to its low-lipophilic profile. METHODS: A pharmacokinetic study included 28 porcine coronary arterial segments initially injured with balloon angioplasty followed by the local delivery of everolimus encapsulated in nanospheres (EEN) via injection through a microporous delivery catheter. The animals were sacrificed at 1 hour, 1,7,28, and 90-day follow-up. In the tissue effects study 16 coronary bare metal stent (BMS) were implanted following EEN delivery, 15 BMS following nanospheres delivery without the drug (reference group) and 16 implanted BMS served as a control. Angiographic and histology follow-up was scheduled at 28 and 90-day. RESULTS: The study showed high-everolimus concentrations in arterial tissue early after nanoparticles delivery followed by its gradual decrease to 1.15 ± 0.40 ng/mg at 90 days. Histology analysis showed favorable biocompatibility and healing profile with comparable area stenosis between groups at both time-points. CONCLUSIONS: The present study demonstrates for the first time the safety, biocompatibility, and long-term retention of everolimus in arterial tissue after single local delivery of biodegradable nanospheres.

Serum C-peptide level correlates with the course of muscle tissue healing in the rabbit model of critical limb ischemia.

AIM: The therapeutic potential of adipose-derived stem cell conditioned medium (ASC-CM) was studied in the rabbit model of critical limb ischemia (CLI). METHODS: Rabbits received treatment with ASC-CM or placebo. Gastrocnemius muscle tissue was collected 35 days after ischemia induction. Ischemic changes were evaluated in hematoxylin-eosin stained tissues for early (necrotic lesions/granulation tissue) and late (fibrous scars) phases of tissue repair. The expression of proangiogenic miR-126 was also evaluated using in situ hybridization. The levels of cytokines, insulin, and C-peptide were measured in blood. RESULTS: Early repair phases were observed more often in placebo-treated samples (45.5%) than in ASC-CM-treated ones (22.2%). However, the difference was not statistically significant. We demonstrated a statistically significant positive correlation between the early healing phases in tissue samples and C-peptide levels in peripheral blood. The expression of proangiogenic miR-126 was also shown in a number of structures in all phases of ischemic tissue healing. CONCLUSION: Based on our results, we believe that treatment with ASC-CM has the potential to accelerate the healing process in ischemic tissues in the rabbit model of CLI. The whole healing process was accompanied by miR-126 tissue expression. C-peptide could be used to monitor the course of the tissue healing process.

Temporal healing patterns and coverage dynamics after new Polish transcatheter PFO occluder implantation in a swine.

BACKGROUND: Although currently used devices for interventional closure of patent foramen ovale (PFO) are widely used due to the minimally invasive nature of this technique and high success rate, there is still a need to look for new materials and designs in order to improve the treatment outcomes. AIM: To evaluate the safety, biocompatibility, temporal healing patterns, and coverage dynamics of the new Polish PFO occluder (Balton, Warsaw, Poland) in a swine model - an observation that may assist the decision with regard to its first-in-human use and duration of anticoagulation therapy. METHODS: In total, 12 pigs were scheduled for 28-day (n = 6) and 90-day follow-up (n = 6). In each animal, using a standard femoral venous approach, one PFO occluder was implanted and subsequently, in order to verify device position stability, the Minnesota manoeuvre was performed. At follow-up, all devices underwent a comprehensive evaluation with the use of high-resolution radiography (Faxitron MX-20 system), scanning electron microscopy (SEM), and standard histopathological techniques. RESULTS: All PFO occluders were implanted successfully with no complications. The Faxitron revealed that all nitinol portions of the frame appeared intact and breaks were not detected at both studied time points. Overall, the device appeared to be well deployed in the atrial septum. At 28 days the average neointimal coverage of the right side of the PFO occluder by SEM was 92%; while in contrast the left side had less coverage, at 63%. At 90 days, the coverage of the right side of the occluder was 96.8%, while the left side of the PFO occluder improved and had similar coverage of 93.3%. By histology the endothelialisation process was virtually complete at 90 days. At the early time-point the overall inflammatory infiltrate was moderate and subsequently it diminished and was only mild or occasionally moderate at 90-day follow-up. At both time points the inflammatory reaction was limited to the neointimal tissue surrounding the device. CONCLUSIONS: Our study confirmed safety and good overall biocompatibility of the new Polish PFO occluder, which is comparable to other devices available on the market - an observation that supports the decision with regard to its first-in-human application. Neoendothelialisation was virtually completed at 90 days, suggesting that similarly to other widely used devices a minimum of three to six months of anticoagulation therapy should be recommended.

Therapeutic Potential of Adipose-Derived Therapeutic Factor Concentrate for Treating Critical Limb Ischemia.

Transplantation of adipose-derived stem cells (ADSCs) is an emerging therapeutic option for addressing intractable diseases such as critical limb ischemia (CLI). Evidence suggests that therapeutic effects of ADSCs are primarily mediated through paracrine mechanisms rather than transdifferentiation. These secreted factors can be captured in conditioned medium (CM) and concentrated to prepare a therapeutic factor concentrate (TFC) composed of a cocktail of beneficial growth factors and cytokines that individually and in combination demonstrate disease-modifying effects. The ability of a TFC to promote reperfusion in a rabbit model of CLI was evaluated. A total of 27 adult female rabbits underwent surgery to induce ischemia in the left hindlimb. An additional five rabbits served as sham controls. One week after surgery, the ischemic limbs received intramuscular injections of either (1) placebo (control medium), (2) a low dose of TFC, or (3) a high dose of TFC. Limb perfusion was serially assessed with a Doppler probe. Blood samples were analyzed for growth factors and cytokines. Tissue was harvested postmortem on day 35 and assessed for capillary density by immunohistochemistry. At 1 month after treatment, tissue perfusion in ischemic limbs treated with a high dose of TFC was almost double (p < 0.05) that of the placebo group [58.8 ± 23 relative perfusion units (RPU) vs. 30.7 ± 13.6 RPU; mean ± SD]. This effect was correlated with greater capillary density in the affected tissues and with transiently higher serum levels of the angiogenic and prosurvival factors vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). The conclusions from this study are that a single bolus administration of TFC demonstrated robust effects for promoting tissue reperfusion in a rabbit model of CLI and that a possible mechanism of revascularization was promotion of angiogenesis by TFC. Results of this study demonstrate that TFC represents a potent therapeutic cocktail for patients with CLI, many of whom are at risk for amputation of the affected limb.

A Nuclear Magnetic Resonance Spectroscopy as a Method for Evaluation of In Vivo Poly-l-Lactide Biodegradation Kinetics From Stent-Polymer Matrices: An Experimental Study Utilizing Porcine Model of In-Stent Restenosis.

OBJECTIVES: We aimed to comprehensively evaluate poly-lactide polymer degradation and sirolimus release kinetics from a drug-eluting stent matrix in the in vivo setting using a nuclear magnetic resonance (NMR) method. METHODS: In 22 domestic swine, 18 biodegradable polymer-only coated stents (BPSs) and 36 biodegradable polymer-coated sirolimus-eluting stents (BP-SES) were implanted in coronary arteries with 115% overstretch. The animals were sacrificed at 1, 3, 7, 14, 28, and 56 days following baseline procedures. Vessel segments with BPS were harvested to evaluate polymer degradation with a NMR method, whereas BP-SES to analyze sirolimus tissue uptake and retention. Additionally, 8 BP-SES were implanted for histological analysis for 90 days of follow-up. RESULTS: The NMR showed a gradual absorption of the polymer over the 6 consecutive time points, from 5.48 µg of the polymer on the stent at 1-day follow-up, through 4.33 µg at 3 days, 3.16 µg at 7 days, 2.42 µg at 14 days, 1.92 µg at 28 days to 1.24 µg in the last day of the study. The curve of polymer degradation corresponds well with the pharmacokinetic profile of sirolimus eluted from its surface and measured at identical time points. In histopathology, at 90 days, complete healing and biocompatibility were reported. CONCLUSIONS: The utilization of NMR method for BP absorption kinetics evaluation is a useful tool, which may be widely adopted to test other biodegradable implants. Further, it may substantially improve their safety and efficacy by facilitating programmed polymer and drugs elution.

Dose-dependent vascular response following delivery of sirolimus via fast releasing, biodegradable polymer stent matrix: an experimental study in the porcine coronary model of restenosis.

BACKGROUND: Fast releasing, rapamycin-eluting stents, although safe, showed inferior results with regard to inhibition of restenosis. AIM: Therefore, we report vascular effects of a novel, biodegradable polymer stent matrix with elevated sirolimus dose and fast release kinetics (ed-frSES, Alex, Balton) in the porcine coronary in-stent restenosis model. METHODS: A total of 19 stents were implanted with 120% overstretch in the coronary arteries of seven domestic pigs: seven ed-frSES with 1.3 µg/mm2 of sirolimus, eight frSES with 1 µg/mm2 of sirolimus, and eight bare metal stents (BMS). For the following 28 days, coronary angiography was performed, animals were sacrificed, and the stented segments harvested for histopathological evaluation. RESULTS: In angiography at 28 days the late lumen loss was lowest in the elevated dose sirolimus eluting stent (SES) (ed-frSES: 0.20 ± 0.2 vs. frSES: 0.80 ± 0.5 vs. BMS: 0.96 ± 0.5 mm, p < 0.01). This was confirmed in the morphometric evaluation in histopathology as represented by a significant and dose-dependent decrease in the percentage area of stenosis (ed-frSES: 22.4 ± 12.7% vs. frSES: 35 ± 10.7% vs. BMS: 47.5 ± 12.5%, p < 0.01). There was no peri-strut inflammation in any of the groups. However, the endothelialisation score was numerically not meaningfully decreased in ed-frSES (ed-frSES: 2.93 vs. frSES: 3. vs. BMS: 3, p = 0.05). Signs of fibrin were also noted in ed-frSES (ed-frSES: 0.4 vs. frSES: 0 vs. BMS: 0, p = 0.05). CONCLUSIONS: Sirolimus dose-dependent vascular response was reported. The elevated dose, fast releasing SES shows satisfactory vascular healing, similar to regular dose, fast release SES, with improved efficacy in restenosis inhibition.

A novel peritoneum derived vascular prosthesis formed on a latex catheter in an SDF-1 chemokine enriched environment: a pilot study.

INTRODUCTION: Although saphenous vein grafts are widely used conduits for coronary artery bypass graft surgery, their clinical value remains limited due to high failure rates. The aim of the study was to evaluate feasibility, safety, and biocompatibility of peritoneal derived vascular grafts (PDVG) formed on a silicone-coated, latex, Foley catheter in a stromal cell-derived factor (SDF-1)- enriched environment. METHODS: Foley catheters were implanted into the parietal wall of 8 sheep. After 21 days the peritoneal cavity was re-opened and the newly formed tissue fragments were harvested. The animals were randomly assigned into: (1) study group in which conduits were incubated in a solution containing SDF-1, (2) control group without SDF-1 incubation. Left carotid arteries were accessed and "end-to-side" anastomoses were performed. Biological materials for histological examination were taken at 4, 7, 10, and 14 days. RESULTS AND CONCLUSIONS: The study proved safety, feasibility, and biocompatibility of PDVG formed on the basis of a silicone-coated, latex catheter in an SDF-1 chemokine-enriched environment. These biological grafts effectively integrated with the native high-pressure arterial environment in an ovine model and provided favorable vascular profile. The potential clinical value of this technology needs to be further elucidated in long-term preclinical and clinical studies.

Safety and biocompatibility of a novel self-expanding nitinol carotid stent with hybrid cell design in a porcine model of neointimal hyperplasia.

BACKGROUND: Stent design may influence the outcomes, suggesting that adverse event rates vary according to free cell area and cell design. Open cell design technology of self-expandable stents, dedicated for carotid revascularisation has better deliverability, although closed cell technology is expected to cause fewer thromboembolic events. AIM: To evaluate the feasibility and vascular response of novel, hybrid cell, self-expandable nitinol stents (MER®, Balton, Poland) implanted into porcine carotid arteries. Hybrid cell design combines open and closed cell technology. METHODS: All tested stents were implanted with 10% overstretch into 10 carotid segments of Polish domestic pigs. Control angiography was obtained immediately before and after vascular interventions as well as 28 days after the procedure. Thereafter, animals were sacrificed, and the treated segments were harvested and evaluated in the independent histopathology laboratory. RESULTS: All stents were easily introduced and implanted, showing good angiographic acute outcome. At 28 days, in the angiography, all vessels were patent with no signs of thrombi or excessive neointimal formation, with the late lumen loss of -0.11 ± 0.3 mm and percentage diameter stenosis 10.18 ± 8.1%. There was a 10% increase in the vessel reference diameter when compared to baseline (4.57 ± 0.5 vs. 4.96 ± 0.3 mm, p < 0.01). In the histopathology, mean area stenosis was 17.4% and mean intimal thickness was 0.20 mm. At histopathology, the mean injury, inflammation, and fibrin scores were low. Endothelialisation was complete in all stents, and neointimal tissue appeared moderately mature as shown by the moderate mean neointimal smooth muscle score. Nonetheless, histopathology shows one stent affected by peri-strut granulomas and one stent affected by marked mineralisation. CONCLUSIONS: The novel Polish self-expandable nitinol carotid stent with hybrid cell technology shows optimal biocompatibility and a vascular healing profile, and therefore may be introduced for first-in-man application.

Differences in vessel healing following delivery of everolimus or paclitaxel: a comparative experimental study using identical stent and biodegradable polymer platforms.

AIMS: We aimed to compare the vascular effects exclusive to antiproliferative agents by using identical stent and biodegradable polymeric matrices eluting everolimus (BP-EES) (Carlo; Balton) and paclitaxel (BP-PES) (Luc-Chopin2; Balton) in the porcine model of coronary injury. A total of 37 stents were implanted with 110% overstretch in the coronary arteries of 14 domestic pigs: 13 BP-PES, 16 BP-EES and eight bare metal stents (BMS) (Chopin2; Balton). Coronary angiography was performed after 28 and 90 days, the animals were sacrificed and the stented segments harvested for histopathological evaluation. At 28 days, BP-PES most effectively limited angiographic late loss (LL PES: 0.15±0.1 vs. EES: 0.40±0.3 vs. BMS: 0.5±0.2 mm; p=0.04) and neointimal thickness (NT) in histology (PES: 0.12 [0.1-0.2] vs. EES: 0.38 [0.3-0.4] vs. BMS: 0.35 [0.3-0.4] mm; p<0.01). The BP-PES had lower endothelialisation (EES: 100% vs. PES: 40±4% vs. BMS: 97.5±5%; p<0.01) and slightly higher inflammation scores (EES: 1 vs. PES: 2.1±0.3 vs. BMS: 1; p<0.01). At three months, LL remained unchanged in the EES and BMS groups in contrast to an increase in the PES group (EES: 0.38±0.3 vs. PES: 0.52±0.4 vs. BMS: 0.51±0.3 mm; p=0.69). NT stabilised at 90 days in the EES group in comparison to a fourfold increase in the PES group and a 30% increase in the BMS group (EES: 0.35 [0.3-0.5] vs. PES: 0.53 [0.5-0.8] vs. BMS: 0.46 [0.4-0.5] mm: p=0.07). Stent endothelialisation and inflammation were comparable at 90 days in all groups. Temporal differences in vascular response were seen by the delivery of different antiproliferative agents. In contrast to everolimus, paclitaxel seems to induce a slightly higher degree of inflammation in the short term, potentially leading to further neointimal hyperplasia in the long term.