Fabrication and in vivo chondrification of a poly(propylene carbonate)/l-lactide-grafted tetracalcium phosphate electrospun scaffold for cartilage tissue engineering

Fabrication and in vivo chondrification of poly(propylene carbonate)/l-lactide-grafted tetracalcium phosphate electrospun scaffold for cartilage tissue engineering.

Delivering instilled hydrophobic drug to the bladder by a cationic nanoparticle and thermo-sensitive hydrogel composite system

Some bladder disease therapies can benefit from intravesical drug delivery, which involves direct instillation of drug into the bladder via a catheter, to attain high local concentrations of the drug with minimal systemic effects. Deguelin is a potential anticancer agent, however, its poor water solubility and neurotoxicity restrict its clinical application. To address these challenges, we investigated the promising application of deguelin in the intravesical therapy of bladder cancer by designing a novel intravesical drug delivery system for deguelin. It was found that deguelin could efficiently kill bladder cancer cells and inhibit angiogenesis. Intravesically administrated deguelin had better tolerance than systemically applied deguelin. Encapsulation of deguelin in cationic DOTAP and monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) hybrid nanoparticles (DMP) created the deguelin loaded DMP nanoparticles (D/DMP). They had a mean particle size of 35 nm and zeta potential of 21 mV, rendering deguelin completely dispersible in aqueous media. Encapsulation of deguelin in cationic DMP nanoparticles enhanced the anticancer activity of deguelin in vitro. In addition, D/DMP nanoparticles were incorporated into a thermo-sensitive Pluronic F127 hydrogel, forming a novel D/DMP-F system, which remained in a flowing liquid state at lower than 25 °C, but underwent gelation at higher temperatures. The DMP nanoparticles in the F127 hydrogel system (DMP-F) could significantly extend the hydrophobic drug residence time and increase the drug concentration within the bladder. These results suggested that DMP-F was a good intravesical drug delivery system and D/DMP-F may have promising applications in intravesical therapy of bladder cancer.

Anticancer effect and mechanism of polymer micelle-encapsulated quercetin on ovarian cancer

Encapsulation of hydrophobic agents in polymer micelles can improve the water solubility of cargos, contributing to develop novel drugs. Quercetin (QU) is a hydrophobic agent with potential anticancer activity. In this work, we encapsulated QU into biodegradable monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelles and tried to provide proof-of-principle for treating ovarian cancer with this nano-formulation of quercetin. These QU loaded MPEG-PCL (QU/MPEG-PCL) micelles with drug loading of 6.9% had a mean particle size of 36 nm, rendering the complete dispersion of quercetin in water. QU inhibited the growth of A2780S ovarian cancer cells on a dose dependent manner in vitro. Intravenous administration of QU/MPEG-PCL micelles significantly suppressed the growth of established xenograft A2780S ovarian tumors through causing cancer cell apoptosis and inhibiting angiogenesis in vivo. Furthermore, the anticancer activity of quercetin on ovarian cancer cells was studied in vitro. Quercetin treatment induced the apoptosis of A2780S cells associated with activating caspase-3 and caspase-9. MCL-1 downregulation, Bcl-2 downregulation, Bax upregulation and mitochondrial transmembrane potential change were observed, suggesting that quercetin may induce apoptosis of A2780S cells through the mitochondrial apoptotic pathway. Otherwise, quercetin treatment decreased phosphorylated p44/42 mitogen-activated protein kinase and phosphorylated Akt, contributing to inhibition of A2780S cell proliferation. Our data suggested that QU/MPEG-PCL micelles were a novel nano-formulation of quercetin with a potential clinical application in ovarian cancer therapy.

Treating colon cancer with a suicide gene delivered by self-assembled cationic MPEG-PCL micelles

Biodegradable cationic micelles show promise for applications in gene delivery. In this article, we used DOTAP to modify monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL, MP) micelles in one step, creating novel cationic self-assembled DOTAP and MPEG-PCL hybrid micelles (DMP). These micelles had a mean particle size of 46 ± 5.6 nm and a zeta potential of 41.8 ± 0.5 mV, and had the capacity to bind DNA. Compared with PEI25K (the gold standard), DMP micelles had higher transfection efficiency and lower cytotoxicity. Moreover, we used DMP to deliver the Survivin-T34A gene (S-T34A, a suicide gene) to treat colon cancer. DMP delivered the Survivin-T34A gene (DMP/S-T34A) and could induce apoptosis in cancer cells, resulting in inhibition of the growth of C-26 colon cancer cells in vitro. An in vivo study indicated that intraperitoneal administration of DMP micelles delivered the Survivin-T34A gene and efficiently inhibited the growth of abdominal metastatic C-26 colon cancer and the malignant ascites. These data suggest that DMP may be a novel gene carrier, and its delivery of the S-T34A gene may have promising applications in the treatment of colon cancer.

PCL/PEG copolymeric nanoparticles: potential nanoplatforms for anticancer agent delivery

Nanotechnology provides researchers with new tools for cancer treatment. Biodegradable polymeric nanoparticles, as an advanced drug delivery system, have promising applications in cancer treatment. Poly(ε-caprolactone)/poly(ethylene glycol) (PCL/PEG) copolymers are biodegradable and amphiphilic, and show potential application in drug delivery. In recent years, PCL/PEG copolymeric nanoparticles, as a potential nanoplatform for anticancer agent delivery, received increasing attention. This paper reviews PCL/PEG copolymer nanoparticles for anticancer agent delivery, including overcoming water insolubility of hydrophobic drug, targeting chemotherapeutic drug to tumor, and delivering genes, vaccines, and diagnostic agents.

Gene therapy for C-26 colon cancer using heparin-polyethyleneimine nanoparticle-mediated survivin T34A

BACKGROUND

Gene therapy provides a novel method for the prevention and treatment of cancer, but the clinical application of gene therapy is restricted, mainly because of the absence of an efficient and safe gene delivery system. Recently, we developed a novel nonviral gene carrier, ie, heparin-polyethyleneimine (HPEI) nanoparticles for this purpose.

METHODS AND RESULTS

HPEI nanoparticles were used to deliver plasmid-expressing mouse survivin-T34A (ms-T34A) to treat C-26 carcinoma in vitro and in vivo. According to the in vitro studies, HPEI nanoparticles could efficiently transfect the pGFP report gene into C-26 cells, with a transfection efficiency of 30.5% ± 2%. Moreover, HPEI nanoparticle-mediated ms-T34A could efficiently inhibit the proliferation of C-26 cells by induction of apoptosis in vitro. Based on the in vivo studies, HPEI nanoparticles could transfect the Lac-Z report gene into C-26 cells in vivo. Intratumoral injection of HPEI nanoparticle-mediated ms-T34A significantly inhibited growth of subcutaneous C-26 carcinoma in vivo by induction of apoptosis and inhibition of angiogenesis.

CONCLUSION

This research suggests that HPEI nanoparticle-mediated ms-T34A may have a promising role in C-26 colon carcinoma therapy.

Preparation of anti-CD40 antibody modified magnetic PCL-PEG-PCL microspheres

Antibody modified magnetic polymeric microspheres have potential biomedical application. In this paper, anti-CD40 antibody modified magnetic poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCL-PEG-PCL, PCEC) microspheres were prepared. First, PCL-PEG-PCL triblock copolymer was synthesized by ring-opening polymerization, followed by reaction with succinic anhydride, creating carboxylated PCL-PEG-PCL copolymer. Then, magnetite nanoparticles were encapsulated into carboxylated PCL-PEG-PCL microspheres, forming magnetic PCL-PEG-PCL microspheres with carboxyl group on their surface. Catalyzed by EDC/NHS, the anti-CD40 antibody was linked to these magnetic PCL-PEG-PCL microspheres, thus forming anti-CD40 modified PCL-PEG-PCL microspheres. These anti-CD40 antibody modified magnetic PCL-PEG-PCL microspheres may have potential application in cell separation.

Curcumin-loaded biodegradable polymeric micelles for colon cancer therapy in vitro and in vivo

Curcumin is an effective and safe anticancer agent, but its hydrophobicity inhibits its clinical application. Nanotechnology provides an effective method to improve the water solubility of hydrophobic drug. In this work, curcumin was encapsulated into monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelles through a single-step nano-precipitation method, creating curcumin-loaded MPEG-PCL (Cur/MPEG-PCL) micelles. These Cur/MPEG-PCL micelles were monodisperse (PDI = 0.097 ± 0.011) with a mean particle size of 27.3 ± 1.3 nm, good re-solubility after freeze-drying, an encapsulation efficiency of 99.16 ± 1.02%, and drug loading of 12.95 ± 0.15%. Moreover, these micelles were prepared by a simple and reproducible procedure, making them potentially suitable for scale-up. Curcumin was molecularly dispersed in the PCL core of MPEG-PCL micelles, and could be slow-released in vitro. Encapsulation of curcumin in MPEG-PCL micelles improved the t(1/2) and AUC of curcumin in vivo. As well as free curcumin, Cur/MPEG-PCL micelles efficiently inhibited the angiogenesis on transgenic zebrafish model. In an alginate-encapsulated cancer cell assay, intravenous application of Cur/MPEG-PCL micelles more efficiently inhibited the tumor cell-induced angiogenesis in vivo than that of free curcumin. MPEG-PCL micelle-encapsulated curcumin maintained the cytotoxicity of curcumin on C-26 colon carcinoma cells in vitro. Intravenous application of Cur/MPEG-PCL micelle (25 mg kg(-1) curcumin) inhibited the growth of subcutaneous C-26 colon carcinoma in vivo (p < 0.01), and induced a stronger anticancer effect than that of free curcumin (p < 0.05). In conclusion, Cur/MPEG-PCL micelles are an excellent intravenously injectable aqueous formulation of curcumin; this formulation can inhibit the growth of colon carcinoma through inhibiting angiogenesis and directly killing cancer cells.

Preparation of magnetic microspheres based on poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) copolymers by modified solvent diffusion method

Magnetic microspheres have promising application in biomedical field. In this paper, biodegradable poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCEC) triblock copolymers were synthesized by ring-opening polymerization method. Through adjusting the epsilon-CL/PEG weight ratio in feed, PCEC copolymers with different block ratio were obtained. A novel modified solvent diffusion method was described to prepare magnetic PCEC composite microspheres containing magnetite nanoparticles. The particle size of microsphere decreased with increase in the PEG/PCL block ratio. The obtained microspheres could response to external magnetic field. This study described a novel method to prepare magnetic microspheres. The obtained magnetic polymeric microspheres might have potential application in drug delivery system or disease diagnosis field.

Improving anticancer activity and reducing systemic toxicity of doxorubicin by self-assembled polymeric micelles

In an attempt to improve anticancer activity and reduce systemic toxicity of doxorubicin (Dox), we encapsulated Dox in monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelles by a novel self-assembly procedure without using surfactants, organic solvents or vigorous stirring. These Dox encapsulated MPEG-PCL (Dox/MPEG-PCL) micelles with drug loading of 4.2% were monodisperse and ∼ 20 nm in diameter. The Dox can be released from the Dox/MPEG-PCL micelles; the Dox-release at pH 5.5 was faster than that at pH 7.0. Encapsulation of Dox in MPEG-PCL micelles enhanced the cellular uptake and cytotoxicity of Dox on the C-26 colon carcinoma cell in vitro, and slowed the extravasation of Dox in the transgenic zebrafish model. Compared to free Dox, Dox/MPEG-PCL micelles were more effective in inhibiting tumor growth in the subcutaneous C-26 colon carcinoma and Lewis lung carcinoma models, and prolonging survival of mice bearing these tumors. Dox/MPEG-PCL micelles also induced lower systemic toxicity than free Dox. In conclusion, incorporation of Dox in MPEG-PCL micelles enhanced the anticancer activity and decreased the systemic toxicity of Dox; these Dox/MPEG-PCL micelles are an interesting formulation of Dox and may have potential clinical applications in cancer therapy.

Efficient inhibition of C-26 colon carcinoma by VSVMP gene delivered by biodegradable cationic nanogel derived from polyethyleneimine

Biodegradable cationic nanoparticles have promising application as a gene delivery system. In this article, heparin-polyethyleneimine (HPEI) nanogels were prepared, and these nanogels were developed as a nonviral gene vector. The transfection efficiency of HPEI nanogels was comparable with that of PEI25K, while the cytotoxicity was lower than that of PEI2K and much lower than that of PEI25K in vitro. These HPEI nanogels also had better blood compatibility than PEI25K. After intravenous administration, HPEI nanogels degraded, and the degradation products were excreted through urine. The plasmid expressing vesicular stomatitis virus matrix protein (pVSVMP) could be efficiently transfected into C-26 colon carcinoma cells by HPEI nanogels in vitro, inhibiting the cell proliferation through apoptosis induction. Intraperitoneal injection of pVSVMP/HPEI complexes efficiently inhibited the abdominal metastases of C-26 colon carcinoma through apoptosis induction (mean tumor weight in mice treated with pVSVMP/HPEI complex = 0.93 g and in control mice = 3.28 g, difference = 2.35 g, 95% confidence interval [CI] = 1.75-2.95 g, P < 0.001) and prolonged the survival of treated mice. Moreover, intravenous application of pVSVMP/HPEI complexes also inhibited the growth of pulmonary metastases of C-26 colon carcinoma through apoptosis induction. The HPEI nanogels delivering pVSVMP have promising application in treating colon carcinoma.

Polymeric matrix for drug delivery: honokiol-loaded PCL-PEG-PCL nanoparticles in PEG-PCL-PEG thermosensitive hydrogel

In this article, we demonstrated a novel injectable polymer matrix: honokiol (HK) loaded poly (epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCL-PEG-PCL, PCEC) nanoparticles in thermosensitive poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) hydrogel for the drug local delivery. First, HK, as a model hydrophobic drug, was loaded into PCL-PEG-PCL nanoparticles by emulsion solvent evaporation method to overcome its poor water solubility. Then, the HK-loaded PCEC nanoparticles (HK-PCEC) were incorporated into thermosensitive PEG-PCL-PEG hydrogel, which was sol at low temperature and could gel as a depot for sustained release of drug in situ after topical injection. The HK-PCEC incorporated PECE hydrogel (HK-PCEC-PECE) was biodegradable and could be gradually eliminated from the injection site in about 2 weeks after subcutaneously injected into mice. The in vitro release studies indicated that HK could be released from HK-PCEC and HK-PCEC-PECE in a sustained manner. Such biodegradable smart drug-delivery system might have great potential application in injectable hydrophobic drug local delivery system.

Honokiol nanoparticles in thermosensitive hydrogel: therapeutic effects on malignant pleural effusion

Honokiol (HK) can efficiently inhibit the growth of tumors. However, its clinical applications have been restricted by its extreme hydrophobicity. We hope to improve its water solubility by nanotechnology. And we wonder whether a novel honokiol nanoparticles-loaded thermosensitive poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) hydrogel (HK-hydrogel) could improve the therapeutic efficacy on malignant pleural effusion (MPE). To evaluate the therapeutic effects of HK-hydrogel on MPE, MPE-bearing mice were administered intrapleurally with HK-hydrogel, HK nanoparticles (HK-NP), blank hydrogel, or normal saline (NS) at days 4 and 11 after Lewis lung carcinoma (LLC) cells inoculation, respectively. Pleural tumor foci and survival time were observed, and antiangiogenesis of HK-hydrogel was determined by CD31. Histological analysis and assessment of apoptotic cells were also conducted in tumor tissues. HK-hydrogel reduced the number of pleural tumor foci, while prolonging the survival time of MPE-bearing mice, more effectively, as compared with control groups. In addition, HK-hydrogel successfully inhibited angiogenesis as assessed by CD31 (P < 0.05). Histological analysis of pleural tumors exhibited that HK-hydrogel led to the increased rate of apoptosis. This work is important for the further application of HK-hydrogel in the treatment of MPE.

Transdermal anaesthesia with lidocaine nano-formulation pretreated with low-frequency ultrasound in rats model

Rapid local transdermal anaesthetic is desirable in clinic. In this paper, lidocaine loaded poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCL-PEG-PCL) nanoparticles were prepared, and a novel transdermal lidocaine formulation: lidocaine loaded PCL-PEG-PCL nanoparticles in F127 hydrogel (Nano-Lido Gel), was demonstrated. These lidocaine loaded PCL-PEG-PCL nanoparticles with mean particle size of ca. 200 nm had drug loading of about 40%. The efficiency of transdermal anaesthesia of four treatments: EMLA cream (E), Nano-Lido Gel (N), EMLA cream with brief focal ultrasound pretreatment (EU), and Nano-Lidocaine Gel with brief focal ultrasound pretreatment (NU), was evaluated by tail-flick latency test assay in rats. Results indicated that the topical anaesthesia onset time in NU was 5 times and 2.5 times shorter than that in E and EU. The efficiency of anaesthesia in NU, expressed as maximum possible effects (MPE) value, was significantly higher than that in other treatments. It provided a novel path to develop rapid transdermal anaesthesia by combination of ultrasound pretreatment and lidocaine nano-formulation based on polymeric nanoparticles.

Preparation of MPEG-PLA nanoparticle for honokiol delivery in vitro

Honokiol (HK) shows potential application in cancer treatment, but its poor water solubility restricts clinical application greatly. In this paper, monomethoxy poly(ethylene glycol)-poly(lactic acid) (MPEG-PLA) was synthesized by ring-opening polymerization and processed into nanoparticle for honokiol delivery. Chemical structure of the synthesized polymer was confirmed by (1)H NMR, and its molecular weight was determined by gel permeation chromatography (GPC). Honokiol loaded MPEG-PLA nanoparticles were prepared by solvent extract method. And particle size distribution, morphology, drug loading, drug release profile and anticancer activity in vitro were studied in detail. The described honokiol loaded MPEG-PLA nanoparticles in this paper might be a novel formulation for honokiol delivery.

A novel composite drug delivery system: honokiol nanoparticles in thermosensitive hydrogel based on chitosan

In this article, a novel composite drug delivery system, honokiol nanoparticles in biodegradable hydrogels based on chitosan (CS) and beta-glycerophosphate (beta-GP), was prepared. CS/beta-GP solution was liquid at room temperature and turned into gel as temperature increased. With increase in beta-GP concentration, the sol-gel transition temperature decreased accordingly. Honokiol nanoparticles with diameter of about 30 nm were prepared by emulsion solvent evaporation method. The sol-gel transition temperature of CS/beta-GP system decreased as F-127 presented in honokiol nanoparticles. In vitro release profiles were studied, the results showed that honokiol could be slowly released from CS/beta-GP gel over at least 2 weeks and the release rate was greatly influenced by initial drug loading. The described injectable hydrogels based on chitosan (CS) and beta-glycerophosphate (beta-GP) might have potential application as local drug delivery for honokiol.

Preparation of biodegradable polycaprolactone/poly (ethylene glycol)/polycaprolactone (PCEC) nanoparticles

Biodegradable polyetherester copolymer (PCL/PEG/PCL, PCEC) was synthesized by ring-opening polymerization of epsilon-caprolactone initiated by poly(ethylene glycol) (PEG). The PCEC nanoparticles were prepared by solvent diffusion method or w/o/w double emulsion method. The obtained particles' morphology was observed on scanning electron microscopy, and the particle size distribution was determined using Malvern laser particle sizer. Bovine serum albumin was used as the model water-soluble protein drug, which was successfully encapsulated in PCEC nanoparticles, the drug release behavior was studied in detail. The hydrolytic degradation behavior of the PCEC nanoparticles was also studied.

Acute oral toxicity evaluation of biodegradable and pH-sensitive hydrogel based on polycaprolactone, poly(ethylene glycol) and methylacrylic acid (MAA)

In this article, a novel biodegradable and pH-sensitive hydrogel based on polycaprolactone, poly(ethylene glycol) and methylacrylic acid (MAA), was prepared by UV-initiated free radical polymerization. The obtained hydrogel was characterized by (1)H NMR and FTIR. The acute toxicity tests and histopathological study were performed in BALB/c mice. In acute oral toxicity test, mice were orally administered with a total 15 g/kg body weight (b.w.) of P(CL-MAA-EG) hydrogels, and were observed continuously for 14 days. For histopathologic study, samples including heart, liver, lung, kidneys, spleen, stomach, and intestine, were histochemically prepared and stained with hematoxylin-eosin for histopathologic examination. No mortality or significant signs of acute toxicity was observed during the whole observation period, and no macroscopic alteration was found in the organs. Histopathological analysis of various organs also did not show any significant pathological changes. Thus, the maximal tolerance dose of P(CL-MAA-EG) hydrogels was calculated to be higher than 15 g/kg b.w. in BALB/c mice. It was suggested that the studied P(CL-MAA-EG) hydrogel in this article were nontoxic after acute oral administration and it might be a promising candidate as a novel oral drug carrier.

Synthesis, characterization and hydrolytic degradation study of polyetheresteramide copolymers based on epsilon-caprolactone, 6-aminocaproic acid, and poly(ethylene glycol)

In this paper, a new kind of biodegradable aliphatic polyetheresteramide copolymers (PEEA) based on epsilon-caprolactone, 6-aminocaproic acid, and poly(ethylene glycol) (PEG) were synthesized by melt polymerization method. The obtained copolymers were characterized by 1H-NMR. The thermal properties of PEEA copolymers were studied by DSC and TGA/DTA under nitrogen atmosphere. The water absorption and hydrolytic degradation behavior was also studied in detail. With the increase in PEG content or the decrease in caprolactone content, the water absorption of the copolymers increased accordingly. For the hydrolytic degradation behavior, with the increase in PEG content or caprolactone content, the degradation rate increased then.

Synthesis, characterization and hydrolytic degradation of degradable poly(butylene terephthalate)/poly(ethylene glycol) (PBT/PEG) copolymers

Hydrolytic degradable PBT/PEG copolymer was synthesized by macromolecular transesterification method from PBT and PEG macromonomers. The resultant copolymers were characterized by (1)H-NMR and GPC. The non-isothermal crystallization behavior of these copolymers was studied by differential scanning calorimetry (DSC). The water absorption and hydrolytic degradation behavior of PBT/PEG copolymers were also studied in detail.

Effects of dynamic cardiomyoplasty on left ventricular systolic and diastolic performance in an acute canine model

Although dynamic cardiomyoplasty (DCMP) is currently being evaluated as an alternative to end-stage congestive heart failure, the overall results of DCMP are variable and inconclusive. We evaluated the effect of classic DCMP on systolic and diastolic cardiac function in normal heart using reliable indicators which minimize the influences of load conditions. Six experimental dogs were evaluated with the acute nonpreconditioning model. The slope of the linear preload recruitable stroke work relationship (Mw) showed a significant increase with latissimus dorsi muscle (LDM) stimulation (postwrap non-stimulation 59.1+/-6.3, postwrap stimulation 98.6+/-9.7 erg cm(-3) x 10(3); P < 0.01), and the x-intercept (V0) was unchanged; these were utilized as the indicators of left ventricular systolic function. The constant of pressure decay (tau) increased after LDM wrap (prewrap 45.8+/-6.0, postwrap nonstimulation 69.3+/-10.3, postwrap stimulation 72.3+/-13.9 ms; P < 0.05), and the peak filling rate was unchanged after LDM wrap, which were utilized as the indicators of diastolic function. We concluded that classic dynamic cardiomyoplasty is effective in assisting systolic cardiac function, but may to some degree have a detrimental effect on the diastolic cardiac function.

Effects of free latissimus dorsi dynamic cardiomyoplasty on left ventricular function

In their experimental approach to dynamic cardiomyoplasty (DCMP), the authors hypothesized that a wrapping method using the proximal part of a free latissimus dorsi muscle (LDM) graft might augment ventricular contractility more than the classic Carpentier's wrapping method. The authors divided 12 mongrel dogs into a pedicled LDM graft group (Group 1, n = 6) and a free LDM graft group (Group 2, n = 6) to evaluate the properties of the different wrapping methods. To evaluate the effect of DCMP on left ventricular systolic and diastolic function, the authors used precise indicators that minimize the influences of load conditions. The slope of the linear preload recruitable stroke work relationship (Mw) and an X-intercept (Vo) were utilized as the indicator of left ventricular systolic function. The constants of pressure decay (tau) and peak filling rate (PFR) were measured to determine diastolic function. All experimental animals were evaluated with the acute, non preconditioning model. Mw was significantly increased with LDM stimulation in both groups (postwrap non stimulation 59.1 +/- 6.3; postwrap stimulation 98.6 +/- 9.7 erg.cm-3. 10(3); p < 0.01 in Group 1, postwrap non stimulation 66 +/- 6.7; postwrap stimulation 155 +/- 15.7 erg.cm-3.10(3), p < 0.001 in Group 2). Stimulated free LDM grafts significantly increased the Mw in comparison to pedicled grafts (p = 0.011). Vo was unchanged in both groups and there was no significant difference between the two groups. Tau increased after LDM wrap in both groups (p < 0.05), but there was no difference between the two groups (tau; prewrap 45.8 +/- 6.0; postwrap non stimulation 69.3 +/- 10.3; postwrap stimulation 72.3 +/- 13.9 msec in Group 1, prewrap 50.0 +/- 6.0; post wrap non stimulation 61.8 +/- 5.0; post wrap stimulation in 64.3 +/- 4.7 msec in Group 2). Peak filling rate was unchanged after LDM wrap in both groups. Free LDM grafts significantly increased left ventricular systolic function compared to the pedicled LDM. Although myocardial relaxation was impaired after LDM wrap in both groups, there was no difference between the two groups. The authors' results emphasize the explicit benefit of utilization of a free LDM graft in respect to left ventricular systolic function; the free LDM grafts have no gross detrimental effect on diastolic function when compared with a pedicle graft in the acute model.

Effects of stimulated free latissimus dorsi muscle graft on LVEDV and LVSW: a new dynamic cardiomyoplasty technique

The effectiveness of dynamic cardiomyoplasty (DCMP) remains controversial. We hypothesized that effectiveness of DCMP using the latissimus dorsi muscle graft (LDMG) depends on the wrapping method. We analyzed pressure-volume relations (PVR), the left ventricular stroke work (LVSW), and the left ventricular end diastolic volume (LVEDV) changes during nonstimulation and stimulation of the LDMG to evaluate the effect of a new wrapping method of DCMP on the LVSW and the LVEDV changes. The new wrapping technique was evaluated in an acute animal experimental model. In 12 mongrel dogs, we performed continuous measurement of the dimensional and pressure dates of the left ventricle (LV) after the DCMP. The measurement was performed 15 min after wrapping during 5 periods. The duration of one measurement period was 15 s. The animals were divided into 2 groups according to the wrapping method. The heart was wrapped with the LDMG using 2 different methods. For Method 1, Carpentier's method, the heart was wrapped primarily with the distal part of the LDMG, the lateral segment. The vasculoneural pedicle of the latissimus dorsi muscle (LDM) was preserved. For Method 2, the LDM was separated, and the vasculoneural pedicle was cut. The medical sternotomy was performed. The thoracodorsal artery of LDMG was anastomosed to the right internal mammary artery, and the thoracodorsal vein was anastomosed to the right atrial appendage. The heart was wrapped primarily with the proximal part of the "free LDMG," the transverse segment. Based on the PVR loops, the changes of the LVSW and the LVEDV in both experimental groups were analyzed. The paired t-test was used for statistical analysis. Using Method 1, the LVSW and the LVEDV showed no significant changes during stimulation (stim) of the LDMG, compared with nonstimulation (nonstim) (LVSW: nonstim, 970 +/- 168 erg x 10(3); stim, 1,181 +/- 203 erg x 10(3); p = 0.126 and LVEDV: nonstim, 36.6 +/- 6.7 ml; stim, 37.2 +/- 6.8 ml; p = 0.36). Using Method 2, the LVSW was increased, and the LVEDV was decreased during stimulation of the free LDMG, compared with nonstimulation (LVSW: nonstim, 694 +/- 117 erg x 10(3); stim, 846 +/- 104 erg x 10(3); p < 0.001 and LVEDV: nonstim, 47.7 +/- 2.8 ml; stim, 46.8 +/- 2.7 ml; p < 0.001). The stimulated free LDMG wrapping of the heart seems to be a more effective wrapping method for DCMP, and it results in an increase of the LVSW and a decrease of the LVEDV, compared with the original Carpentier's method.