A Practical Guide to Class IIa Medical Device Development

There are many beneficial medical device ideas based on clinical needs and laboratory research, but medical device development is an expensive, time-consuming and complex challenge. Research and quality management, which are both needed to develop a medical device, are two distinct fields, initiated by a researcher or a clinician having a concept for a medical device, and it is often challenging to find and achieve the proper steps to create a licensed product. Thus, in this paper, we demonstrate the required mindset and main steps of the medical device development procedure through an existing example, a Class IIa medical device, called hypACT Inject Auto. HypACT is a specific syringe, which is capable of blood drawing and serum from platelet-rich fibrin (SPRF) isolation in one step in a closed system. SPRF is intended to be used to improve joint functions in the case of musculoskeletal diseases, specifically osteoarthritis.

becomes a flat membrane inside the device. Attaching a needle onto the end of the device allows the physician to inject the SPRF directly to the knee of the patient. Besides the device, only blood drawing needles and a swing-rotor centrifuge for 50 mL conical centrifuge vials are needed for the treatment.
As medical device development is an expensive, difficult and time-consuming process, in this article we aim to demonstrate the main processes, scheduling and required mindset of medical device development, manufacturing and regulation steps on the actual steps of a Class IIa medical device development. We used this HypACT device to demonstrate the steps of medical device development. We intend to give an impression on the complexity of the processes [38], requirements and human resources that need to work together in order to achieve a medical device product. The demonstrated development was presented from a technological point of view, with the addition of the mandatory regulatory and quality management (QM)-related requirements in the realization of an actual medical device that was put on the market.

1.
At first, the intended use of the medical device must be defined. The intended use is the primary use purpose of the product, including medical indication and patient group. 2.
Next, the functional requirement is formulated. The requirements will form the basis for the development of the system and be used to verify and validate the design changes. These requirements need to be translated to functional requirement specifications, which will become design inputs for manufacturing.

3.
The design input is the base of the device planning and engineering-it means that the actual parameters regarding operation (usage, risk, standards) and physical appearance of the device are created. The parameters needed for implementation, such as the characteristics and dimensions of the product, are collected as functional requirement specification ( Table 1). The design output consists of drawings, specifications and manufacturing instructions-it describes all parts of the device. These will become part of the design and development documentation of the device and therefore also part of the technical documentation. 4.
Prototypes are prepared according to the design output and the approved prototype can go into small quantity production. The produced devices are to be used mainly for process validation. Sterilisation and packaging plans must be finalized, and then these need to be validated as well. The design output is suggested to be patented if the medical device is novel, inventive and industrially applicable.

Quality Management and Regulatory
A quality management system (QMS) is required for medical device certification, preferably according to ISO 13485. Compared to the technological point of view, the QMS focuses on reducing risks and ensuring that the processes are foreseeable and adequately documented, and thus controllable throughout the complete lifecycle of the device.
The quality management and regulatory steps are the following: 1.
Complying risks and hazards and their management according to ISO 14971.

2.
Classification of the device according to the applicable medical device regulations (MDR), based on the markets that are planned to be accessed. In our example, the EU is the main focus. The classification is based on the risks relating to the device-there are three main classes, Class I, Class II and Class III. This determines if the device needs to be sterile, and gives a basic idea on the magnitude of the costs and complexity of the device. 3.
The essential requirements (general safety and performance according to the new MDR) of the devices and all the processes that are in connection with the device are regulated by standards and it is required to be gathered according to the applicable medical device directives (MDD) and regulations ( Table 2). Essential requirements are divided into two parts-Part I: general requirements and Part II: requirements for design and construction. A checklist can be obtained through the Official Journal of the European Union to identify the applicable standards. All the process validations need to be performed that are required in the applicable standards and regulations after the design and development phase is over.

4.
Biological evaluation needs to be performed according to ISO 10993-1 to ensure from biological and toxicological aspects, and that the use of the device is safe for both the patient and the users ( Table 3).

5.
Accomplishing clinical evaluation. Clinical evaluation is either the analysis and demonstration of equivalence [39] using publicly available clinical data regarding the clinical, technical and biological characteristics of the medical device compared to relevant medical devices on the market, or performing a clinical investigation [40] to determine its clinical safety and effectiveness, that is stated in the intended use.

1.
The intended use of the medical device: The device was developed to accomplish point of care therapy for knee osteoarthritis. It is suitable to draw blood from a patient, and after a physical separation, a concentrated growth factor containing autologous serum (serum from platelet-rich fibrin, SPRF) is isolated aseptically in a closed system. In cases when the physician intends to use SPRF, this serum fraction can be isolated in an aseptic way by the device and injected to the knee of the patient immediately.

2.
The user needs were collected and used to create the functional requirement specifications. The user needs were found to be the following: • Device can be used in medical facilities.

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The device can be used in autologous therapy.

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The plunger can be pulled by one or two fingers.

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The device has to withstand drawing and injecting therapeutically useful amounts of blood.

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The clotted serum fraction can be separated from the red blood cells.

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The device has to fit in a centrifuge bucket where a 50 mL conical centrifuge tube fits.

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Needles or butterfly needles can be attached to the syringe.

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The device shall not leak.

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The device shall be used to draw blood from human patients and the contents of the syringe are compatible to be used therapeutically.

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The device can be stored prior to use without any changes occurring.

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Can be centrifuged at high speed for a short period of time.

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Liquid from the clotted serum shall be pressed out.

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No infection occurs when using the device.

3.
Design input and output The user needs were converted to functional requirements (Table 1). These were translated to design inputs based on physical parameters, essential requirements and risks. Visualization of the ideas and intensive and constructive communication were conducted between the in-house or contractual developer and the initiator by the fabrication of desk models and prototypes, which resulted in the design outputs. An example to demonstrate a part of the final version of the design outputs of the device can be seen in Figure 1. To simplify the regulatory process, each part of the device is made of approved medical device grade materials.
• The device has to withstand drawing and injecting therapeutically useful amounts of blood.

•
The clotted serum fraction can be separated from the red blood cells.

•
The device has to fit in a centrifuge bucket where a 50 mL conical centrifuge tube fits. • Needles or butterfly needles can be attached to the syringe.

•
The device shall not leak.

•
The device shall be used to draw blood from human patients and the contents of the syringe are compatible to be used therapeutically.

•
The device can be stored prior to use without any changes occurring.

•
Can be centrifuged at high speed for a short period of time.

•
Liquid from the clotted serum shall be pressed out.

•
No infection occurs when using the device.

Design input and output
The user needs were converted to functional requirements (Table 1). These were translated to design inputs based on physical parameters, essential requirements and risks. Visualization of the ideas and intensive and constructive communication were conducted between the in-house or contractual developer and the initiator by the fabrication of desk models and prototypes, which resulted in the design outputs. An example to demonstrate a part of the final version of the design outputs of the device can be seen in Figure 1. To simplify the regulatory process, each part of the device is made of approved medical device grade materials.

4.
Review and Validation The development process ends with the fabrication of a prototype that was prepared according to the finalized design output, and is accepted by the legal manufacturer. This is followed by a mandatory design review and small quantity production (300-1000 units) can begin for process and manufacturing validations, which were determined by the applicable standards and regulations, e.g., as the above-mentioned biological evaluation. Besides the manufacturing related processes, that need to be validated, two processes need special attention-these are sterilisation and packaging. In the present case, the device was sterilised using ethylene-oxide, due to the glass constituent, which would become amber coloured if gamma radiation was used, thus the sterilisation method was validated according to EN 1422:2014, as listed in Table 2. It is important to note that not all medical devices need to be sterilised-this requirement needs to be evaluated according to the classification of the device. The packaging of the device consists of a tray (as seen in Figure 2, made of Poly (ethylene terephthalateco-1,4-cylclohexylenedimethylene terephthalate (PETg)) and a Tyvek lid (Tyvek 1073B), and the packaging was tested according to the applicable standards. Packaging validation needs to be performed with special care, as packaging needs to be reliable, being the first and most important barrier throughout the whole lifecycle of the device to ensure sterility from the end of manufacturing during transportation and storage until the device is used by the end user.
The packaging, labelling and instructions for use need to be created according to the applicable standards and are considered as parts of the device; thus, after the medical device design is finalized, then the whole packaged device needs to pass the technology-related process validations. Therefore, the description of the device, also called as the instructions for use (IFU) needs to be part of the design and has to be placed within the packaging before the validation begins.
As an example, the main part of the IFU of the present device can be seen in Figure 2. The design of the present device was patented in the EU; the identification number of the granted patent is EP3383269B1.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 8 of 15 can be pressed out from the syringe using the plunger; approximately 4.8 mL SPRF can be isolated using one device.

Demonstration of Quality Management and Regulatory Steps and Path
Research and development have to be conducted from different aspects as usual. A quality management system (QMS) is required; it is recommended to write it according to ISO 13485. The QMS has to be prepared parallel with technical documentation. The device must be developed and manufactured in accordance with the requirements of all applicable standards and regulations. The main aspects are listed below: 1. Risks and hazards and their management need to be identified and the probability of occurrence needs to be reduced to as low as possible according to ISO 14971, Annex E of EN. can be pressed out from the syringe using the plunger; approximately 4.8 mL SPRF can be isolated using one device.

Demonstration of Quality Management and Regulatory Steps and Path
Research and development have to be conducted from different aspects as usual. A quality management system (QMS) is required; it is recommended to write it according to ISO 13485. The QMS has to be prepared parallel with technical documentation. The device must be developed Appl. Sci. 2020, 10, 3638 8 of 14 and manufactured in accordance with the requirements of all applicable standards and regulations. The main aspects are listed below:

1.
Risks and hazards and their management need to be identified and the probability of occurrence needs to be reduced to as low as possible according to ISO 14971, Annex E of EN.

2.
Classification of the device: in our case, the device was classified according to Annex IX of 93/42/EEC (MDD): The device was categorized as a Class IIa device using rule 3 of the directive. Rule 3: "All non-invasive devices intended for modifying the biological or chemical composition of blood, other body liquids or other liquids intended for infusion into the body are in Class IIb, unless the treatment consists of filtration, centrifugation or exchanges of gas, heat, in which case they are in Class IIa". 3.
The essential requirement checklist we used for our device according to MDD can be seen in Table 2.

4.
Biological evaluation Biological evaluation was accomplished with the use of Table 3. according to ISO 10993-1. The required tests, that are needed to assure that the device is safe are listed, are based on the nature of contact and the duration of the contact. In our case, the biological evaluation path is highlighted in green.

5.
Clinical evaluation In our case, clinical evaluation was achieved by proving equivalence to a product that is already used. We used manually produced SPRF to compare to hypACT SPRF using mesenchymal stem cells with the exact methods and results which can be seen below. Preparation of different supplementation containing media As positive control stem cell medium (FBS medium), as negative controls serum-free medium and human serum albumin (Behring, King of Prussia, Pennsylvania, USA)-containing medium (HSA medium) were used. Phlebotomy occurred under ethical approval (IRB approval number: 33106-1/2016/EKU, 12.07.2016) from healthy donors, men and women, aged 24-45 years. SPRF was isolated using the device as shown in Figure 2 (device SPRF). The device SPRF contains a small amount of red blood cells, which may be harmful to cell viability. They can be eliminated by another centrifugation at 1700 g for 8 min after isolation (twice centrifuged device SPRF). The reference SPRF was isolated manually. Fifty millilitres of blood was drawn using an ordinary syringe and the blood was poured into a centrifuge tube, containing 10 g glass beads as glass surface to promote blood clotting. It was immediately centrifuged at 1700 g for 8 min, while the fibrin matrix was formed.
To squeeze out SPRF from the fibrin matrix, it was centrifuged again at 1700 g. Each cell culture media contained 10% supplementation, except for serum-free and HSA medium, where the amount of HSA was normalized to the protein content of SPRF.

5.3
Comparing the effect of different serum containing media on MSC cell viability MSCs (4 passages) were seeded onto 24 well plates at a density of 1500 cells/well in 500 µL stem cell medium and the culture medium was changed on the first day to the different supplementation containing media. The medium was changed every two days. Images were taken by an inverse fluorescent Nikon microscope.

Results
The results of XTT measurement (Figure 3) do not show any significant differences between device SPRF, twice centrifuged device SPRF and glass bead SPRF. One-way analysis of variance (ANOVA) with Tukey's post hoc test was performed to compare the means of groups using Prism 7 software. The significance level was p < 0.05 and data are presented as mean ± SEM (n = 4). The results of microscopic imaging show ( Figure 4) that MSCs cultured in the three kinds of SPRF media reached roughly similar density in the wells and they have the same MSC-like shape.

Evaluation
The main conclusion of the clinical evaluation was that the blood separation product prepared by our device is at least as safe to use as a PRF isolation method that is already used in the practice, thus that is a way to claim clinical safety of the device. However, the optimal path to investigate clinical safety of medical devices needs to be evaluated on a case-by-case basis; nevertheless, the present path was applicable for the device. However, due to the requirements of the MDR, clinical equivalence may become more rare and actual clinical investigations will need to be done more often in the future.

Results
The results of XTT measurement ( Figure 3) do not show any significant differences between device SPRF, twice centrifuged device SPRF and glass bead SPRF. One-way analysis of variance (ANOVA) with Tukey's post hoc test was performed to compare the means of groups using Prism 7 software. The significance level was p < 0.05 and data are presented as mean ± SEM (n = 4).
The results of microscopic imaging show ( Figure 4) that MSCs cultured in the three kinds of SPRF media reached roughly similar density in the wells and they have the same MSC-like shape. Figure 3. Viability of cells cultured in different serum-containing media. There is no significant difference between SPRF containing media regarding mesenchymal stem cells (MSC) viability. The significance level was p < 0.05, where * means that the p-value was between 0.05 and 0.01, ** means that the p-value was between 0.01 and 0.001, and *** means that p-value was lower than 0.001.

Evaluation
The main conclusion of the clinical evaluation was that the blood separation product prepared by our device is at least as safe to use as a PRF isolation method that is already used in the practice, thus that is a way to claim clinical safety of the device. However, the optimal path to There is no significant difference between SPRF containing media regarding mesenchymal stem cells (MSC) viability. The significance level was p < 0.05, where * means that the p-value was between 0.05 and 0.01, and *** means that p-value was lower than 0.001. investigate clinical safety of medical devices needs to be evaluated on a case-by-case basis; nevertheless, the present path was applicable for the device. However, due to the requirements of the MDR, clinical equivalence may become more rare and actual clinical investigations will need to be done more often in the future.

Conclusions and Discussions
In summary, the present work aimed to give a basic insight into how to initiate, plan and execute medical device product development. The main conclusion is the importance of planning and proper

Conclusions and Discussion
In summary, the present work aimed to give a basic insight into how to initiate, plan and execute medical device product development. The main conclusion is the importance of planning and proper awareness of the requirements that are needed for medical device development. Before one decides to start a medical device project, careful planning needs to take place, which evaluates the scope and requirements, the timelines of the development and the human resource need, e.g., the knowledge and skills that are available in-house, which are the ones that need training and which ones need to be outsourced. This article presents the medical device development from a technology-based point of view; however, creating a budget for the whole project is the most important to be realistic. From this viewpoint, the importance of the planning phase becomes easier to understand, as the planning phase costs several hundred thousand euros, whereas the actual development, based on the complexity and safety requirements of the device, is in the million-euro range, from the initial medical device conception until when the product is available on the market.

Patents
The device was patented as Apparatus for Preparing Blood Fraction Concentrate by István Hornyák and Zsombor Lacza, the patent number is EP3383269B1.