BIOPR1NTED GRAFT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on, and claims the benefit of priority to U.S. provisional application no. 62/373,165, filed AUGUST 10, 2016, the entire contents of which are incorporated herein by reference.

FIELD OF THE DISCLOSURE

[0002] The present disclosure relates generally to a method of repairing a tissue perforation using a custom 3D bioprinted graft.

DESCRIPTION OF THE RELATED ART

10003 j Eardrum perforations are problematic as they cause complications including conductive hearing loss and chronic foul ear drainage (i.e., otorrhea) from repeated infections. These complications occur in 3 to 5% of cases after ear tube placement as well as in cases of acute otitis media, a second most common infection in pediatrics, chronic otitis media with or without cholesteatoma, or as a result of barotrauma to the ear.

[0004] Perforations are most problematic when they cause both conductive hearing loss and chronic ear drainage, which can be debilitating and socially isolating to patients. Although some perforations heal spontaneously, most persist despite dry ear precautions, ototopical drops, or myringoplasty and must undergo surgical repair.

[0005] Tympanoplasty is a surgical procedure to repair a defect in the tympanic membrane with the placement of a graft and is performed over 55,000 times each year in the United States alone. The goal of this surgical procedure is to close the perforation, thereby preventing infection from contaminated water and improving hearing. The success of surgical procedure is critically dependent on a surgeon's ability to measure the shape of the defect, hand-cut an appropriately sized graft, and accurately place it.

[0006] Defects of the tympanic membrane can be marginal or central, and typically are 2 to 10 mm across. Smaller perforations of the tympanic membrane can result in low-frequency hearing loss, while larger perforations can cause both high-frequency and low-frequency hearing loss. This hearing loss makes it difficult to listen effectively in learning enviiOnments and social gatherings with background noise.

[0007] Chronic infections, mastoiditis, and even cholesteatoma can result from perforations of the tympanic membrane. In addition, perforation creates a significant risk of developing otitis when swimming in lakes, rivers, oceans, or pools. For children and adults who enjoy water sports, wish to swim on vacation, or participate in pool parties, this can be debilitating and socially isolating.

[0008] Although various techniques have been developed for perforation repair, the cartilage grafting techniques have a reported success rate of 43% to 100%. Cartilage can be harvested easily from the outer ear, the tragus, or the concha! bowl. Tragal cartilage is harvested with perichondrium attached via a small incision on the internal surface of the tragus. This graft must be carved free-hand to the appropriate size, which can be extremely difficult with irregularly shaped perforations.

[0009] During the tympanoplasty, the surgeon estimates the size of the graft with spare ear suction or a right-angled hook or a ruler (Figure 2B). All of these instruments have inherent flaws as none of them is specifically designed to measure the size of small tympanic defects. This leads to significant inaccuracies, which explains the variable rates of graft success. A wide variability (43-100%) in success indicates a need for new techniques to ensure a perfectly fitting graft to fit into the tympanic membrane for the perforation repair.

9 [0010] Another key factor for the success of the perforation repair is care ul placement of the graft, which must precisely fit into the defect with negligible overlap onto the drum (Figures 2C and 2D). The graft has to be perfectly sized to fit into the circumferential groove of the tympanic remnant. Without a perfectly contoured and sized graft the surgery is destined to fail and the graft will not snap into place. For example, if the defect is sized too small, then the graft will not cover the defect. Conversely, if the graft is sized too big, then the graft will not fit in place. As a result, it is essential to craft a graft to within 1 mm accuracy, which is extremely difficult to do using the current manual procedure.

SUMMARY

[0011] This disclosure provides a system and method for creating a 3D bioprinted graft for repair of a tissue perforation or defect based on a scan of the tissue perforation or defect.

[0012] The system for creating a 3D bioprinted graft including a tablet having a custom software application that is configured to capture an image from an endoscope and allow the surgeon to outline the defect. The application is configured to create a 3D model that will be sent to a 3D bioprinter to print the graft, which can then be implanted directly in the ear.

[0013] The bioprinted graft can increase the success of eardrum repair, which would improve and normalize a patient's hearing, and eliminate the risk of ear infection from water exposure. Current techniques for eardrum repair are suboptimal due to the manual nature of the procedure.

[0014] This disclosure provides an example of the invention used for an eardrum repair, however, this invention can have broader applications to other medical pathologies such as intestines for microperforations, brain covering (Dura mater) for determination of potential Cerebrospinal Fluid (CSF) leaks, and vascular systems to determine arterial wall damage prior to aneurysm rupture in strokes. Further this technology can be used for pediatric applications.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0016] FIGS. 1 A and IB show diagrams of a method for creating a 3D bioprinted graft according to an example;

[0017] FIG. 2A shows a perforated tympanic membrane according to an example;

[0018] FIG. 2B shows a manual measurement of dimensions o the perforated tympanic membrane according to an example;

[0019] FIG. 2C shows a cartilage graft that is manually cut according to an example;

[0020] FIG. 2D shows the cartilage graft that is manually cut implanted in the perforation according to an example;

[0021] FIG. 3 is an image of a 3D bioprinter according to an example;

[0022] FIG. 4 shows an implanted bioprinted graft into the perforated tympanic membrane according to an example; and

[0023] FIG. 5 shows an exemplary computer according to an example.

[0024] Like reference numerals designate identical or corresponding parts throughout the several views.

DETAILED DESCRIPTION

[0025] The present disclosure relates to a system for address a problem in the ear. For instance, the system images a tympanic membrane. This imaging may merely provide a two dimensional representation of the membrane from the outside or may obtain further information about the membrane such as the thickness of the membrane. The system further detects a defect such as a hole and the size of the defect in the membrane from the image(s) having a reference and/or based a predetermined knowledge of the size and/or based on an average size and/or based on additional size information provided by a sensor such as a structure sensor. The system additionally generates a model of the defect, such as a hole, and a model of a graft to be inserted into the defect. The graft is bioactive and supports the growth of tissue through and/or around the graft. The graft may be yielding and thus expand after being compressed before insertion into the defect or may be more ridged and be "snapped" into place by being slightly larger than the defect on the outside but smaller on the inside (grommet shaped). Based on the model, the graft is bioprinted (e.g. 3D printed) and then may be inserted into the defect. After a period of time the defect disintegrates as new tissue growth replaces the graft.

[0026] As previously discussed, tympanoplasty is the surgical technique to repair a defect in the tympanic membrane with the placement of a graft. The goal of this surgical procedure is to close the perforation, thereby preventing infection from contaminated water and improving hearing. The ability to accurately fix and repair an eardrum hole is critically dependent on a surgeon's ability to measure the size and shape of defect so they can accurately carve a graft. Although various techniques have been developed for this procedure, the cartilage grafting techniques have a varying reported success rate of 43% to 100%.

[0027] However, as a result of the present disclosure, the time consuming step of manually measuring the defect size with a ruler is eliminated.

[0028] An EARgraft system is provided including a sensor configured to capture images of the defect, an EARgraft application configured to control display of the defect and to receive a set of graft dimensions and a position of cells, biomaterials and corresponding synthetic cartilage materials from the surgeon. The EARgraft application is also configured to convert the set of graft dimensions and the position of cells, biomaterials and corresponding synthetic cartilage materials to a set of instructions for printing the graft on a 3D biological printer (bioprinter). The set of instructions for printing the graft is transferred to the bioprinter.

[0029] Bioprinting is a technology in the field of tissue engineering, which enables fabrication of constructs with precise control of the position of cells, biomaterials, and biochemical signals to recreate complex tissues and organs. Bioprinting is well suited for tympanoplasty as the eardrum consists of heterogeneous tissue with complex cellularity, mechanical properties, and biochemical signals.

Sensors

[0030] hi an example, the sensor can be a video camera configured to capture images through an endoscope. In another example, the sensor can have two video cameras or a feature such that the sensor is configured to capture 3D images and stereo images through the endoscope. The sensor can also be an integrated part in an endoscopic system.

Processing circuitry and resulting programmed functions

[0031] In an example, the EARgraft application is configured to import the image of the ear from an endoscope view and to control display of the image on the tablet. Further, the EARgraft application is further configured to capture images from the endoscope and allow the surgeon to precisely outline the defect, including a defect size with a sub-millimeter level of accuracy. In an aspect, the EARgraft application will allow the surgeon to view the images from the endoscope on the tablet in real-time and select an image for capture at any time. The EARgraft application configured to control display of a user interface for the surgeon to outline the defect. In an example, the surgeon can outline the defect using a touch pen configured to communicate with the tablet. In another example, the surgeon can outline the defect using an augmented/virtual reality input. [0032] In an example, the EARgraft application can be written in Microsoft Visual C++ and can be run on a tablet computer or tablet such as a Microsoft Surface Tablet. However, the tablet can be any other computer having processing power to smoothly run the EARgraft application and to receive input from the surgeon.

[0033] The tablet can include a USB port for interfacing with a peripheral device such as a video capture device and a frame grabber. An example of a video capture device is the DVI2USB from Epiphan Systems. The video capture device is configured to connect to the endoscope and to capture the images for viewing and storage on the tablet. In an example, the video capture device can be a frame grabber configured to capture the image from a Storz endoscope.

[0034] In an example, the video capture device can include a fiduciary marker configured to provide a calibration scale at the defect. The fiduciary marker can be an optical projection on portions of the tissue surrounding the defect. In another example, the surgeon can place a ruler at the same level as the defect and in view of the endoscope image. Similar to the fiduciary marker, the EARgraft application will use the ruler to calibrate the graft size after outlining by the surgeon.

[0035] In an aspect, the video capture device is configured to determine a thickness of the tissue and the tissue perforation. In an aspect, the tablet can be configured to determine a shape of the tissue perforation based on a 2D image. In an example, the shape of the tissue perforation based on a 2D image can be determined by an edge detection algorithm.

[0036] Once a sufficient image is captured, the surgeon can use a touch pen or mouse to precisely outline the defect. In an example, the EARgraft application can be configured to provide the exact dimensions of the defect. In an aspect, the application can allow the surgeon to zoom in as much as desired to improve the precision of the outline. When the surgeon is satisfied that the defect is precisely outlined, the application will generate a set of instructions to create the graft based on the user input. In an example, the application is configured to convert the image file format to a stereolithography (STL) format used by the 3D bioprinter, which can be transferred by a memory stick.

3D bioprinter

[0037] The system includes a bioplotter or bioprinter having one or more synthetic cartilage materials. The bioprinter is configured to receive a set of instructions for printing the graft and to print the graft using the one or more synthetic cartilage materials based on a set of instructions. The set of instructions for printing the graft can include the set of dimensions, a position of cells, biomaterials and corresponding synthetic cartilage materials, and biochemical signals to recreate complex tissues and organs. The printed graft can subsequently be implanted directly into the perforation for a precise fit. FIG. 4 shows a tympanic membrane 410 and an implanted bioprinted graft 420 into the perforated tympanic membrane according to an example. In an aspect, since the grafts are small, they can be printed quickly. An example of a bioprinter is an EnvisionTec 3D Bioprinter shown in Figure 3.

Biomaterials

[0038] The graft can be a bioprmted gelatin-based implant. In an example, the graft can be a patient- specific tissue engineered 3D constructed tympanic membrane (3D-TETM) based on gelatin methacrylate (GelMA) 3D-printing platform. The bioprinter is configured to print 3D constructs with precise resolution ( l OOum) and with demonstrated control over the position and orientation of the biomaterials, which is particularly relevant in the area of tympanic membrane regeneration.

[0039] In an example, the biomaterials include Epidermal growth factor (EGF), which is a cytokine that has been shown to promote tympanic membrane regeneration. EGF is a negatively charged protein and can be encapsulated in the GelMA to promote tissue regeneration. In an example, the EGF can be configured to be encapsulated in and sustainably released from GelMA. GelMA is an excellent biomaterial for tissue regeneration because it is biocompatible, nontoxic, biodegradable, and allows for quick integration with host cells and tissues.

[0040] By modulating the concentration of catalysts and polymer concentration, the mechanical properties of printed GelMA can be tuned to regenerate different tissues including the tympanic membrane.

[0041] Furthermore, depending on the synthesis method, GelMA can be positively or negatively charged. Therefore, a sustained-release of biochemical signals can be achieved through electrostatic interactions.

[0042] To achieve a sustained release of EGF, GelMA can be synthesized using type A gelatin (positively charged), and printed into a 3D-TETM. In an aspect, EGF can be used to stimulate tympanic membrane regeneration by recruiting and stimulating proliferation of epithelial cells from the host. When delivered with a gelatin-based scaffold, GelMA can significantly enhance tympanic membrane closure in animal models with neovascularization.

[0043] Fibroblast migration is a critical process in wound closure. An amount of epidermal growth factor or EGF amount can be selected to support a dose-dependent fibroblast migration rate within the implant (e.g. bioprinted gelatin hydrogel). In an example, the EGF amount is configured to 0, 6, 13 μΜ in order to support dose-dependent fibroblast migration rates of 40.7±100, 51.8±112, 120±102 μηι day respectively. In another example, the EGF amount is varied based on an amount of mesenchymal stem cell delivered.

Biomechanics

[0044] In an example, the method for creating a 3D bioprinted graft for repairing a tissue perforation includes determining the dimensions of the graft based biomechanics. In an aspect the graft is configured to withstand up to 4.67±2.22 kPa of pressure without displacement. The graft can be pressure tested by a puncture test according to an example. In an aspect, varying dimensions of the graft can be modeled in order to repair the perforation. In an example, the EARgraft application can be configured to suggest modifying the perforation in order to improve the biomechanics of the graft,

synthetic model

[0045] A synthetic model can be used for testing prior to implanting the customized cartilage graft. The synthetic model can be composed of a sheet of cadaveric tissue (alloderm in blue) with a perforation (in red) that can be used to capture and validate the accuracy of the measurements with the tympanic telescope and print out of the appropriate reconstructive templates with the 3D biopr inter (ear gram).

[0046] A chinchilla ear closely resembles that of the human ear both in anatomy and method of transmitting sound information to the brain. As such, the chinchilla is the gold standard animal model for experimentation related to ear pathology. A chinchilla has a large external ear allowing easy placement of the ear graft and a prominent ear bone, bulla, facilitating pathological examination of eardrum integrity. The bulla is a bone surrounding the hearing organ in chinchillas. This large, thin bone is easily located allowing for additional ease of pathological examination of eardrum integrity.

Functional assessment

[0047] After one week, the implanted graft can be re-examined to confirm integrity of the perforation repair. At four weeks, endoscopic images and audiological testing can be used to confirm if the graft is properly functioning.

[0048] Each of the functions of the described embodiments may be implemented by one or more processing circuits. A processing circuit includes a programmed processor (for example, processor 1703 in Fig. 5), as a processor includes circuitry . A processing circuit also includes devices such as an application-specific integrated circuit (ASIC) and circuit components that are arranged to perform the recited functions.

[0049] The various features discussed above may be implemented by a computer system (or programmable logic). Fig. 5 illustrates such a computer system 1701. In one embodiment, the computer system 1701 is a particular, special-purpose machine when the processor 1703 is programmed to perform the estimate computations and other functions described above.

[0050] The computer system 1701 includes a disk controller 1706 coupled to the bus

902 to control one or more storage devices for storing information and instructions, such as a magnetic hard disk 1707, and a removable media drive 1708 (e.g., floppy disk drive, readonly compact disc drive, read/write compact disc drive, compact disc jukebox, tape drive, and removable magneto-optical drive). The storage devices may be added to the computer system 1701 using an appropriate device interface (e.g., small computer system interface (SCSI), integrated device electronics (IDE), enhanced-IDE (E-IDE), direct memory access (DMA), or ultra-DMA).

[0051] The computer system 1701 may also include special purpose logic devices

(e.g., application specific integrated circuits (ASICs)) or configurable logic devices (e.g., simple programmable logic devices (SPLDs), complex programmable logic devices (CPLDs), and field programmable gate arrays (FPGAs)).

[0052] The computer system 1701 may also include a display controller 1709 coupled to the bus 1702 to control a display 1710, for displaying information to a computer user. The computer system includes input devices, such as a keyboard 171 1 and a pointing device 1712, for interacting with a computer user and providing information to the processor 1703. The pointing device 1712, for example, may be a mouse, a trackball, a finger for a touch screen sensor, or a pointing stick for communicating direction information and command selections to the processor 1703 and for controlling cursor movement on the display 1710.

[0053] The processor 1703 executes one or more sequences of one or more instructions contained in a memory, such as the main memory 1704. Such instructions may be read into the main memory 1704 from another computer readable medium, such as a hard disk 1707 or a removable media drive 1708. One or more processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in main memory 1704. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions. Thus, embodiments are not limited to any specific combination of hardware circuitry and software.

[0054] As stated above, the computer system 1701 includes at least one computer readable medium or memory for holding instructions programmed according to any of the teachings of the present disclosure and for containing data structures, tables, records, or other data described herein. Examples of computer readable media are compact discs, hard disks, floppy disks, tape, magneto-optical disks, PROMs (EPROM, EEPROM, flash EPROM), DRAM, SRAM, SDRAM, or any other magnetic medium, compact discs (e.g., CD-ROM), or any other optical medium, punch cards, paper tape, or other physical medium with patterns o holes.

[0055] Stored on any one or on a combination of computer readable media, the present disclosure includes software for controlling the computer system 1701, for driving a device or devices for implementing the features of the present disclosure, and for enabling the computer system 1701 to interact with a human user. Such software may include, but is not limited to, device drivers, operating systems, and applications software. Such computer readable media further includes the computer program product of the present disclosure for performing all or a portion (if processing is distributed) o the processing performed in implementing any portion of the present disclosure.

[0056] The computer code devices of the present embodiments may be any interpretable or executable code mechanism, including but not limited to scripts, interpretable programs, dynamic link libraries (DLLs), Java classes, and complete executable programs. Moreover, parts of the processing of the present embodiments may be distributed for better performance, reliability, and/or cost.

[0057] The term "computer readable medium" as used herein refers to any non- transitory medium that participates in providing instructions to the processor 1703 for execution. A computer readable medium may take many forms, including but not limited to, non-volatile media or volatile media. Non-volatile media includes, for example, optical, magnetic disks, and magneto-optical disks, such as the hard disk 1707 or the removable media drive 1708. Volatile media includes dynamic memory, such as the main memory 1704. Transmission media, on the contrary, includes coaxial cables, copper wire and fiber optics, including the wires that make up the bus 1702. Transmission media also may also take the form of acoustic or light waves, such as those generated during radio wave and infrared data communications.

[0058] Various forms of computer readable media may be involved in carrying out one or more sequences of one or more instructions to processor 1703 for execution. For example, the instructions may initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions for implementing all or a portion of the present disclosure remotely into a dynamic memory and send the instructions over a telephone line using a modem. A modem local to the computer system 1701 may receive the data on the telephone line and place the data on the bus 1702. The bus 1702 carries the data to the main memory 1704, from which the processor 1703 retrieves and executes the instructions. The instructions received by the main memory 1704 may optionally be stored on storage device 1707 or 1708 either before or after execution by processor 1703.

[0059] The computer system 1701 also includes a communication interface 1713 coupled to the bus 1702. The communication interface 1713 provides a two-way data communication coupling to a network link 1714 that is connected to, for example, a local area network (LAN) 1715, or to another communications network 1716 such as the Internet. For example, the communication interface 1713 may be a network interface card to attach to any packet switched LAN. As another example, the communication interface 1713 may be an integrated services digital network (ISDN) card. Wireless links may also be implemented. In any such implementation, the communication interface 1713 sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

[0060] The network link 1714 typically provides data communication through one or more networks to other data devices. For example, the network link 1714 may provide a connection to another computer through a local network 1715 (e.g., a LAN) or through equipment operated by a service provider, which provides communication services through a communications network 1716. The local network 1714 and the communications network 1716 use, for example, electrical, electromagnetic, or optical signals that cany digital data streams, and the associated physical layer (e.g., CAT 5 cable, coaxial cable, optical fiber, etc.). The signals through the various networks and the signals on the network link 1714 and through the communication interface 1 713, which carry the digital data to and from the computer system 1701 may be implemented in baseband signals, or carrier wave based signals.

[0061] The baseband signals convey the digital data as unmodulated electrical pulses that are descriptive of a stream of digital data bits, where the term "bits" is to be construed broadly to mean symbol, where each symbol conveys at least one or more information bits. The digital data may also be used to modulate a carrier wave, such as with amplitude, phase and/or frequency shift keyed signals that are propagated over a conductive media, or transmitted as electromagnetic waves through a propagation medium. Thus, the digital data may be sent as unmodulated baseband data through a "wired" communication channel and or sent within a predetermined frequency band, different than baseband, by modulating a carrier wave. The computer system 1701 can transmit and receive data, including program code, through the network(s) 1715 and 1716, the network link 1714 and the communication interface 1713. Moreover, the network link 1714 may provide a connection through a LAN 1715 to a mobile device 1717 such as a personal digital assistant (PDA) laptop computer, or cellular telephone.

[0062] While aspects of the present disclosure have been described in conjunction with the specific embodiments thereof that are proposed as examples, alternatives, modifications, and variations to the examples may be made. It should be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise

[0063] Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.