"BP as a New Device for Surgery and Solid Cancer and Hematopoietic System Tumors Treatment. Effects of BP Implantation"

The Buckypaper (BP) is an innovative material that has attracted the attention of many research groups engaged in the study of its possible applications in various technological fields preliminary to human experimentation. In fact the experimentation, preliminary conducted on animal model, will be applicable to human, if the results in terms of toxicity and durability will be comfortable.

The interesting material properties, such as good mechanical strength, electrical conductivity, low density, porosity adaptable, are closely associated to the intrinsic characteristics of carbon nanotubes (CNTs), of which BP is made . The high surface development of CNT, in addition to promoting their aggregation, allows the preparation of micro-and nano-porous membranes that exclude the passage of colloidal particles with a diameter greater than 50 nm. The microporous structure, also gives the BP high capacity to absorb liquids, such as water, for which the effect of capillarity, penetrates quickly in the mesh material . This could be a possible interpretation of the rapid and effective adhesion of BP to biological tissues observed in our studies on the effects of the material implanted in vivo. The bioadhesion of BP has been documented in ex vivo experiments mechanical peeling (bench surgery), conducted in advance using as substrate, guinea pig, rats, the abdominal muscle fascia of rabbits. The results showed that the force required the posting of BP from organic support is much greater than that required for the conventional prosthesis made from polymer networks, commonly used in hernia surgery fixed with glue and biological prosthetic material bioadhesive synthetic currently marketed . Based on these assessments and based on the potential offered by the use of BP in the field of prosthetic surgery, deductible by the intrinsic characteristics of the material in this project is expected to further research for the development of a new generation of prosthetic materials for use surgical -based BP, easily implantable by the surgeon without the need for sutures, graphs and / or biological glues . The reasons are:

1. stitches: they could tighten the knot vessels (ischemia-atrophy) or nerves (chronic pain);
2. graphs: placing blind and can cause bleeding or pain;
3. biological glues: derived from the plasma of donors and thus could transmit diseases unknown.

It is still unknown if BP has the appropriate mechanical properties to withstand the stresses that occur on the abdominal wall and In any case is documented the good bio-adhesion on living tissues and anatomical preparations, but only if made humid.

For this reason it was decided to prepare composite materials BP/polypropylene. Such materials, defined as "coupled", will be obtained by adhering on the smooth face of BP, a polymeric support which confers to the hybrid film, the correct mechanical resistance. Such a system may be subject to further changes. Indeed, exploiting the functional groups present or introduced into the crystalline structure of MWCNTs and/or on the polymer, it will be possible to implant on the muscle/muscular fascia surface, the composite material, to obtain gripping. Moreover, biologically active molecules, with functions antimicrobial, anti-adhesive, anti-inflammatory or analgesic, can be introduced into the crystalline structure of MWCNTs, for modulate the inflammatory response and the incorporation of the implanted material in the fibrous scar.

The objective of this project is to obtain results that can direct the search for the ultimate realization of a prosthetic device for use in abdominal surgery appliable to humans.

Our Research Group proposes that the present research program has all the skills to achieve all the objectives .

It brings together researchers with proven expertise and experience in various fields of General Surgery and Prosthetic Surgery of abdominal wall and Experienced scientist of Materials Science especially of polymeric nature, also for biomedical uses, Organic Chemistry, and synthesis of bio-conjugates for the development of slow release systems of drugs, characterization of biological systems through techniques of nuclear magnetic resonance (NMR). The surgeon in the unit of search, in fact, for many years been engaged both in the resolution of issues related to surgical techniques, both in the assessment of the effects on the living organism of conventional prosthetic materials and innovative ones, in the proposed project, including through in vivo testing, conducted according to a protocol specially prepared and approved by the Ministry of Health.

The protocol have been drawn in the respect of environmental policies, and ethical principles on experimentation on animal model, in accordance with the guidelines of the European Union (86/609/EEC-European Economic Community), and the Italian Law n° 116/92.

Will be conducted systematic experiments in 30 New Zealand female rabbits (R1-R30), weighting about 3000 g (Harlan Laboratories). The "in vivo" investigations will be about the biocompatibility and the adhesion of BP in the abdominal scar and in the performing of the intervention of incisional hernia and plastic surgery of the inguinal hernia.

The biocompatibility of the BP will be investigated by means of blood chemistry tests. Blood samples of 3 ml of whole blood will run to every beast after induction of general anaesthesia, from the ear vein, before surgery with prosthetic implant, and prior to euthanasia as indicated in the Time schedule.

Methodology and technique of the experiment :

These experiments are preliminar to human use and will be performed under general anesthesia with endotracheal intubation, then hair removal, disinfection and preparation of the surgical field. A midline incision of about 10 cm navel-pubis will be performed, splaying of the skin and subcutaneous layers, then will be incised the fascia plane, and muscles deep to enter in the peritoneum sac. The execution of the blood sampling coincident with the detection of the body weight and the execution of ultrasound of the abdominal region for the study of the implant site in search of signs of sepsis and incisional hernia.

We will implant this kind of new matherials on humans but before to this we will try to study the tollerability and toxicity on an animal model so drawn: ten rabbits (hereafter defined as BPR1-BPR10) (Buckypaper Rabbit subject 1 to 10) will receive 2x2cm2 samples of BP (Buckypaper) and ten rabbits will receive 2x2cm2 samples of PR (polypropylene) (PRR11-PRR20) in a pocket created between muscular fascia and large muscles of the abdominal wall. In five rabbits (BPR21-BPR25), the surgical incision will carried out on the abdominal linea alba and performed deeply, for entering into the abdominal cavity. The control group (R26-R30) will not undergo to surgery.

A 2x2cm2 BP sample will then be inserted with the rough side facing the parietal peritoneum surface and the smooth and brilliant surface facing to the visceral peritoneum (BPR21-BPR25). Five rabbits (R26-R30) will not be operated but will be used as control group. The animals will be monitored and controlled daily, during the entire studied period, in order to continually assess their state of health, and body weight. At the 35th day will be picked up a blood sample for examination. Finally the animals will be sacrificed under general anesthesia.

The cases BPR1-BPR10 (group A) will be compared with the PRR11-PRR20 (control group B) comparing the effects of implants of BP and the same size in Parietene already in use in reconstructive surgery of healthy man . After the intervention, that will last about 60 minutes from the time of induction, the animal will be slowly awakened and then brought back in the room housing.

At the time of sacrifice will be prepared anatomic samples of all the viscera and of the implantation site, to be studied histologically. Histopathological samples for microscopic examination will be prepared. Portions of BP implanted in BPR 1-BPR 10 will be excised with all the surrounding fascia, dermal and muscular tissues. The same procedures will be performed, also in PRR 11-PRR 20 group and BPR 21-BPR 25 group. The samples will be fixed in 10% buffered formalin, cut and stained with Haematoxylin and Eosin (H\&E) for histological observation.

The post-operative pain, as in the human, it will be mild, and will be treated with analgesics according to techniques standardized in humans. In our experience, the animals undergo to prosthetic surgery, both the experimental and the control group, will treated with prophylactic antibiotics and pain medication in the immediate post -operative, and will be closely watched.

Even if in animal model, the sterility of all the surgical procedure prevents inflammation, edema and sepsis and abscesses and ensures a low level of postoperative pain. The days after the surgical procedure is expected a moderate appetite of the operated animals and mild clinical symptoms related to the post-operative .

All treated animals will be observed daily to carefully control the amount of food that will be consumed and thus the potential loss of appetite. Will be look for evidence of possible inflammatory and degenerative processes affecting the skin of the abdominal wall, the symptoms of infection or rejection of the prosthesis. If weight loss will be excessive (eg more than 10% of the normal weight of an animal of the same race, the same age and in comparison to the control group), or the animal will show clinical symptoms of suffering more than a normal postoperative, will be subjected to general anesthesia and then deleted.

The analgesic and antibiotic therapy performed in the postoperative period will be as follows :

Antibiotic : enrofloxacin 2.5 mg /kg /day I.M. for 5-7 days; and anti-inflammatory analgesic : ketoprofen, Findol 10%, 0.3 ml/10kg/die i.m. for 3-5 days. If necessary will be given also tramadol, 2-4 mg /kg/day in the first 2 /3 days post-intervention . The surgical wound will be checked daily.

The clinical-chemical parameters examined from blood samples of 3 ml will be: BUN (Blood Urea Nitrogen), blood glucose, creatinine, sodium, potassium, calcium, magnesium, albumin, total proteinemia and Blood protein level, SGOT(Serum Glutamic Oxaloacetic Transaminase), SGPT(Serum Glutamic PyruvateTransaminase), GGT(gamma glutamyl transferase), ALP(alkaline phosphatase) and fractionated bilirubin, PT(Prothrombin Time), APTT/PTT(Activated partial thromboplastin time), Fibrinogen, CBC(Complete Blood Count) formula, lymphocyte subpopulations, C-reactive protein, erythrocyte sedimentation rate.

Will be performed ultrasound examination to evaluate morphologically the prosthesis' incorporation, the formation of seroma, bruises, abscesses. This procedure will be performed under sedation and followed by body weight check and the pick-up of a blood sample. The same procedure will be repeated twice at the intervention and after 35 days at the sacrifice.