Gel-forming system for removing urinary calculi and fragments thereof

Abstract

Primarily described are gel-forming systems, consisting of or comprising a composition (A), comprising one or several cationically crosslinkable polymer(s), and a composition (B), comprising one or several crosslinking agent(s) for crosslinking the cationically crosslinkable polymer(s) for use in a method for removing urinary calculi and/or fragments thereof, more particularly kidney stones and/or fragments thereof, from a region of the urinary tract, more particularly a kidney, that contains urinary calculi and/or fragments thereof, more particularly kidney stones and/or fragments thereof, that are to be removed, with the following steps: (i) providing the compositions (A) and (B), (ii) introducing the compositions (A) and (B) into a region of the urinary tract, more particularly the kidney, that contains urinary calculi and/or fragments thereof, more particularly kidney stones and/or fragments thereof, that are to be removed, under conditions enabling crosslinking of the cationically crosslinkable polymer(s) upon contact of composition (A) with composition (B) so that a crosslinked gel is formed that partly or fully surrounds the urinary calculi and/or fragments thereof, more particularly kidney stones and/or fragments thereof, that are to be removed, (iii) removing the crosslinked gel together with the urinary calculi and/or fragments thereof, more particularly kidney stones and/or fragments thereof, that are surrounded by it from the urinary tract, more particularly the kidney.

Claims

1. A method comprising: fragmenting one or more urinary calculi in a region of a urinary tract so that a plurality of urinary calculus fragments are formed; and after fragmenting, introducing composition (A) and composition (B) into the region of the urinary tract that contains the plurality of urinary calculus fragments, wherein composition (A) comprises one or more cationically crosslinkable polymers, wherein composition (B) comprises one or more crosslinking agents for crosslinking the one or more cationically crosslinkable polymers, wherein in response to the composition (A) and the composition (B) coming into contact with each other and under conditions enabling crosslinking of the cationically crosslinkable polymers, a crosslinked gel is formed that partly or fully surrounds at least one urinary calculus fragment of the plurality of urinary calculus fragments, and removing the at least one urinary calculus fragment with all of the crosslinked gel still partly or fully surrounding the at least one urinary calculus fragment.

2. The method according to claim 1, wherein the one or more of the cationically crosslinkable polymers of the composition (A) are selected from a group consisting of polyuronides, alginates, pectins and sodium carboxymethyl cellulose (CMC).

3. The method according to claim 1, wherein the one or more of the crosslinking agents of the composition (B) are selected from a group consisting of divalent cations and trivalent cations.

4. The method according to claim 1, wherein the composition (B) has an acidic pH-value in the range of 3.5 to 4.5.

5. The method according to claim 1, wherein at least one of the composition (A) and the composition (B) includes magnetizable particles, and the method further comprising introducing a composition (C) that contains magnetizable particles into the region of the urinary tract that contains at least one of urinary calculi and fragments of urinary calculi in a time delayed manner or at the same time with the composition (A) or the composition (B) so that the crosslinked gel additionally contains magnetizable particles.

6. The method according to claim 5, wherein the magnetizable particles are selected from particles comprising ferromagnetic elements.

7. The method according to claim 1, wherein one or more urinary calculi are one or more of kidney stones, urinary calculus fragments, kidney stone fragments, wherein the urinary tract is a kidney.

8. The method according to claim 1, wherein introducing composition (A) and composition (B) comprises introducing composition (B) before introducing composition (A).

9. The method according to claim 5, wherein the magnetizable particles are selected from particles comprising at least one of iron, nickel, cobalt, AlNiCo, SmCo, Nd.sub.2Fe.sub.14B, Ni80Fe.sub.20, NiFeCo Fe.sub.3O.sub.4, and -Fe.sub.2O.sub.3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Modification strategy for CMC (carboxymethyl cellulose) with DOPA and one of the amino acids summarized under R (bottom box); the used amino acids are partially protected; from left to right: 3,4-Dihydroxyphenylalanine, N-Boc-lysine, t-butyl-cysteine, histidine.

(2) FIG. 2: Photo documentation of a mixture of catechol-modified carboxymethyl cellulose (blackish-brown hydrogel, top) and of the enzyme-free reference hydrogel (ivory, bottom, represented in grey here) on parafilm under the influence of gravity over time.

DETAILED DESCRIPTION

EXAMPLE 1

Manufacture of Compositions (A), (B) and (C)

(3) For manufacture of an exemplary composition (A), 2 g of alginate are dissolved in 200 mL of water.

(4) For manufacture of an exemplary composition (B), an aqueous solution of FeCl.sub.3 (1M) as well as a water-based chitosan solution (0.32 wt.-%, pH 6) and a solution of oxalic acid in water (1M) are initially produced. Approx. 5 drops of the oxalic acid solution are added to 3 mL of the chitosan solution and to this mixture 0.5 mL of iron chloride solution are added.

(5) For manufacture of an exemplary composition (C), a particle suspension in water or physiological buffer containing 4 to 40 mM iron (0.35 to 3.5 per liter) is prepared (M. Geppert et al., Nanotechnology 22 (2011) 145101). This solution is added to A or B to 1% to 50%.

EXAMPLE 2 (EXPERIMENT)

Gel Formation with Modified Biopolymers Using an Amino Acid-Carboxymethyl Cellulose-Hybrid as an Example

(6) The alginate-like sugar derivative sodium carboxymethyl cellulose (CMC) was functionalized with the amino acids DOPA, lysine, cysteine and histidine (FIG. 1), respectively. The DOPA-modified CMC was mixed with the amine functional polysaccharide chitosan and the hydrogel that is formed via electrostatic interaction between the differently charged sugars is examined for its adhesive properties. Moreover, all of the amino acid-cellulose-hybrids were mixed to obtain jellies and the composite strength upon adhesion to titanium was tested. The aim of the experiments was to improve the adhesive properties of the (exemplary) hybrids in a moist environment in order to alter the inclusion of the urinary calculi and fragments thereof, respectively, and the flexibility of the adhesive.

(7) Two different substitution grades were aimed at for the functionalization with DOPA. Each mole of CMC has got eight moles of acetate groups. Related to that, it was modified with half per mil (PA-S6) on the one hand and with 0.3 equivalents of DOPA (PA-S7) on the other hand.

(8) The sodium carboxymethyl cellulose (CMC) was firstly functionalized with the amino acid 3,4-dihydroxyphenylalanine (DOPA) according to an unconventional procedure [1]. Therefore, first of all 2 g of CMC (2 mmol) were dissolved in 30 mL of dd-water over the course of 90 min at 40 C. The pH of the solution of approx. 7 was adjusted to a pH of 4-5 with an aqueous HCl-solution (2 N). 19 mg of EDC (0.1 mmol) and 12 mg of NHS (0.1 mmol) were added to the viscous solution. After 30 min, 20 mg (0.1 mmol) of DOPA, dissolved in 1.5 mL of dd-water, were added dropwise and slowly over a fine syringe while the solution was stirring continuously. The solution was kept stirring overnight.

(9) 10 mL of this solution were removed (PA-S6). A further 2 mL of the solution were lyophilized for ATR analysis. The remainder of the solution (ca. 18 mL) was reactivated for 30 min with 1.1 g of EDC (5.8 mmol) and 0.7 g of NHS (6.1 mmol). An acidic solution of 0.6 g of DOPA (3 mmol) in 10 mL of dd-water and 1 mL of an aqueous HCL solution (2 N) were added slowly via a fine syringe, as done previously for PA-S6, while ensuring good mixing. An ATR was obtained of this solution PA-S7 as well.

(10) The product (PA-S6) was mixed in equal parts with a fresh 0.3% chitosan solution (pH 6). The mixture was divided into two vessels. To one of the two mixtures, 0.5 v % of a fresh laccase solution (1 mg/mL) was added. Both mixtures were mixed well and subsequently locked lying on top of a heatable agitating plate. The shaker was programmed to a run time of four hours at 47 C. and 650 rpm.

(11) The DOPA-CMC-chitosan solution (PAChi) and the DOPA-CMC-chitosan solution in presence of the peroxidase laccase (PAChiLA) that initiates the crosslinking of the catechols, were incubated in order to alter the properties of the expected hydrogels. Thereby, elastic hydrogels formed in both reaction vessels.

(12) Both samples with (PAChiLA) and without laccase (PAChi) were examined regarding their different adhesion potentials. Therefore, one sample (PAChiLA; PAChi) was applied to parafilm, respectively, and the test installation was aligned orthogonally. Thereby, gravity acts on the adhesive surface between the cellulose hydrogel and the surface of the parafilm. The paths lengths that the samples covered due to the gravity that acted on them over time were recorded photographically (FIG. 2).

(13) The hydrogel of the reference was characterized by an ivory-like color, whereas the catechol containing hydrogel that was polymerized with the aid of laccase had a brownish-black color. This discoloration is characteristic for polyphenols and is indicative of an oxidation of the DOPA group on the CMC polymer backbone.

(14) Through the amines offered by the chitosans, the formation of a covalent network as a result of Michael reactions with amines and radical additions might have taken place. The formation of a hydrogel for the reference of the catechol containing cellulose with chitosan without enzyme can be explained by an electrostatic interaction between the carboxylic acids of the carboxy cellulose that are still available and the amines of the chitosan. Subsequently, both hydrogels were examined in a functional experiment regarding the differences in their macroscopic adhesive properties on parafilm. Under the influence of the force vector gravity, the interaction forces gave way to a varying degree as can be read from the covered path lengths. The results of the photo documentation show a stronger adhesion of the crosslinked hydrogel to parafilm in comparison with the reference that is not covalently crosslinked and was incubated without enzyme.

(15) These results support the assumption that the DOPA-CMC-chitosan (PAChi), which is present in an oxidized from, may not be a covalently crosslinked hydrogel. The connection between adhesion and the changes in the sugar matrix provoked by the catechol open up controllable properties of the hydrogel. The purely electrostatically interacting networks rearrange themselves within the hydrogel and give way under the influence of the force vector. This phenomenon is known as creep behavior for thermoplastics.

(16) The enzymatically oxidized DOPA-CMC-chitosan (PAChiLA) has got covalent crosslinks within the hydrogel and as a result of acting shear forces is limited in reorientation. Furthermore, interactions between the polyphenols in the hydrogel network with the polyolefins and paraffin waxes inside the parafilm might occur.

(17) The functionalization of the carboxymethyl cellulose was extended beyond the catechol DOPA to three further amino acids (FIG. 1). The aim of this diversification was to improve the adhesive properties in moist environment through combination of these hybrids

(18) For the synthesis, first of all 13.5 g of CMC (14 mmol) were weighed into a 1 L beaker and dissolved in 550 mL of dd-water under slight stirring at 40 C. After 90 min the clear yellowish solution was cooled to room temperature under stirring. As described above, the present CMC was partly converted into the N-succinimide active ester by using EDC/NHS. After approx. 40 min, the reaction mixture was divided in five Erlenmeyer flasks 83 mL (ca. 2 g CMC). Then, 40 mmol of the amino acid were added to one of the reaction vessels, respectively.

(19) 76 mg of DOPA or 60 mg of histidine, respectively, were solvated beforehand in 100 L HCl (2N) and 1900 L dd-water, respectively. 95 mg of H-Lys(Boc) or 83 mg of H-Cys(tBut)-OH*HCl, respectively, had to be taken up in 2 mL of dd-water in order to preserve the protecting group. As a reference, one sample without the addition of an amino acid was carried through. After 24 hours the reactions were stopped and in stages 10 mL each of the solution were lyophilized.

(20) The extraction of the product with ether was forgone, since the errors caused by potential impurities are inside the error margin of the functional experiment. Under the aspect that this experiment is dedicated to the assessment of adhesive interactions on a macroscopic level, this would seem plausible. The resulting products (PX) were stored at 20 C. The nomenclature is summarized in table 1.

(21) TABLE-US-00001 TABLE 1 Nomenclature of the synthetized CMCs, PX; a) Mixture of PH, PC, PA and PK (15:20:30:35). Amino acid DOPA Lysine Cysteine Histidine Mix.sup.a Amino acid- PA PK PC PH PHCAK P0 CMC-hybrid

(22) The resulting amino acid-cellulose-hybrids were prepared as jellies, respectively. Additionally, a mixture of the modified CMCs of all of the four amino acids in a ratio of PH:PC:PA:PK 15:20:30:35 were used (PHCAK). These jellies were filled into a cell culture plate and submitted to a preliminary study regarding the required curing conditions.

(23) Based on the results of the preliminary study, two bond strength studies for examining the adhesion to titanium were prepared. In study A, the pure jelly (P0) was joined with titanium under saltwater besides the catechol-containing jelly (PA) and the cysteine-modified jelly (PC) as well as the mixture PHCAKV. The saltwater solution was, after joining the samples, laced with FeCl.sub.3 as oxidizing agent.

(24) In study B, samples with the same jellies were joined. However, they were pre-treated (primed) with FeCl.sub.3, i.e., the substrates were wetted with FeCl.sub.3 solution and dried. Afterwards it was proceeded in an analogous manner to study A, however, without addition of FeCl.sub.3 to the saltwater solution.

(25) After four days of storage, the samples were tested, whereby the specimens of study B showed immediate adhesion malfunction.

(26) The specimens of study A were evaluated with a bond tester in six-fold measurements. The mixture PHCAK showed similar adhesion strengths as the testing of the reference (ca. 2 N). PA showed a barely measureable adhesion (ca. 1 N). The adhesion samples that were joined with PC, lead to adhesion malfunction in all of the cases and did not survive the detachment from the joining device.

(27) The fracture surfaces show an orange brown discoloration of the hardened jellies in all cases. This discoloration mainly appears close to the edges. Furthermore, large parts that were wetted with jelly, are not discolored and were present in a gel-like consistency. The samples that longest withstood the shear forces, show adhesive failure in large parts of the wetted region. Cohesive failures only appear occasionally (ca. 5%) close to the edges.

(28) The premature adhesive failure of the PC samples can be explained by the lack of potential reaction partners such as catechols. Nevertheless, it remains open why these joinings as well as the ones of PA adhere worse than the reference.

(29) The tested adhesive samples show clear evidence for the cause of the flexible joining in the fracture surfaces. Rigid regions can only be found close to the edges, which are in individual cases to be interpreted as witnesses of a cohesive failure. The red brown discoloration is caused by the complexed iron ions. The regions that are further away from the edge are still visibly present in the form of a gel. These areas thus do not contribute any cohesion to the bond strength.

(30) This also expressed itself in the progression of the force-time diagram of the shear test (not shown). It could be derived from the parabola like function that it involved a non-hardened adhesive. This effect was also confirmed by Cha et al. [2]. They had expressed a mussel protein via bacteria and performed the posttranslational modification of the tyrosine in the flask. The adhesive joinings with unmodified proteins showed a similar parabola like progression.

(31) Whereas the catechol containing samples (after posttranslational oxidation by tyrosinase) displayed the typical curve, in which a bond dissociation can be determined by a quick decrease of the force that acts against the applied shear force.

(32) A more detailed view at the fracture surfaces reveals why these joining were not able to harden homogeneously. The hardening is, similar to the case of a polyurethane, diffusion controlled. From a critical thickness, in this case the distance from the edge, the hardening stops because of the absence of the required iron ions. This dependence of the hardening from complexation was examined strikingly in a corresponding experiment, the hydrogel study. Since in this case no joining parts restrict the jellies, the hardening progress could be documented photographically. The result of the sample for mixture PHCAK displayed the most homogeneous hardening process of all of the samples. The results of the corresponding storage of the gel pellets in saltwater that was laced with a FeCl.sub.3 solution gave the most homogeneous hardening progress for the pellets of PHCAK as well as in study A regarding the bond strength.

(33) [1] Leung, A. C. W.; Hrapovic, S.; Lam, E.; Liu, Y.; Male, K. B.; Mahmoud, K. A.; Luong, J. H. T. small 2011, 7, 302-305.

(34) [2] Cha, H. J.; Hwang, D. S.; Lim, S.; White, J. D.; Matos-Perez, C. R.; Wilker, J. J. Biofouling 2009, 25, 99-107.

EXAMPLE 3

Application of a Gel-Forming System According to the Invention

(35) An aditus to the lumen of the urinary tract (e.g., to the pelvicocaliceal system) is created either ureterorenoscopically (via the urethra, bladder or ureter) or percutaneously (via skin puncture at the flank). A specific port (a metal shaft if applicable) with an inner diameter of 3 to 9 mm is placed therein. An endoscope is inserted into the urinary tract lumen (e.g., into the pelvicocaliceal system) via the created aditus shaft, the surgical area is inspected and the urinary calculus or urinary calculi, respectively, is/are visualized. The urinary calculus or urinary calculi, respectively, is or are smashed by means of a holmium laser. The large and medium sized fragments are removed with the aid of a calculus catching instrument. 10 mL of a composition (B) according to example 1 are mixed with 1 mL of a composition (C) according to example 1 in a mixing syringe. Subsequently, a catheter is inserted via the endoscopy device (through the aditus) and the mixture of the compositions (B) and (C) is injected into the region of the urinary tract (e.g., into the pelvicocaliceal system) that contains the fragments of the smashed urinary calculus or calculi, respectively. The catheter is flushed with 0.9% NaCl solution and 10 mL (or more or less as required) of a composition (A) according to example 1 are applied, whereby the gel formation occurs over the course of approx. 1 min. Then a grasping instrument is inserted via the surgical endoscope via the aditus shaft. The solidified gel is grasped in one piece or in several parts with the grasping instrument and removed from the body via extraction.