**2. Cell Products must follow FDA regulatory guidelines**

#### **2.1. FDA's risk-based approach**

To protect the public from risks associated with cell therapies and demonstrate the effective‐ ness of treatments, the U.S. FDA and other professional societies such as the ISSCR, and the United States Pharmacopia (USP), have established guidelines for therapies using human cellular and tissue-based products (HCT/Ps). The FDA has statutory authority to prevent the spread of communicable diseases granted under Section 361 of the Public Health Service Act (PHS Act, 42 U.S.C. § 264). HCT/Ps are regulated through a risk-based approach outlined predominantly in 21 C.F.R. Part 1271. Some HCT/Ps are regulated solely under Part 1271 while other HCT/Ps are regulated under both Part 1271 and FDA's Federal Food, Drug, and Cosmetic Act (FDCA, premarket and post- market regulation of medical devices and drugs), & section 351 of the PHS Act for biological products. FDA's regulation focuses on three general areas: 1) limiting the risk of transmission of communicable disease from donors to recipients; 2) establishing manufacturing practices that minimize the risk of contamination; 3) requiring an appropriate demonstration of safety and effectiveness for cells and tissues that present greater risks due to their processing or their use [6, 7].

Stem cell therapies show excellent promise for many types of treatments. However, scientific, manufacturing and safety challenges exist. Once the optimal stem cell type is identified for a given treatment (Table 1), there is a requirement to demonstrate the product's safety and efficacy in a clinical setting. Cell therapies must overcome several challenges before they can be considered safe for human use. First, most cell therapies will require large numbers of cells. Large cell doses are obtained by increasing cell harvest yields and by increasing ex vivo expansion yields. As cell cultures are expanded over long time periods, they show signs of aging that may be similar to human aging [8, 9]. Lengthy expansion periods can result in ineffective cellular products[10]. Cells may also be manipulated in other manufacturing steps that include cell-selection processes, genetic modifications, or encapsulation with another biological device. Cells that undergo ex vivo manipulation may lose potency, or acquire infectious contaminants, or become trans‐ formed / tumorogenic due to the cell culture conditions [11, 12]. Finally, the cells them‐ selves may pose a risk, simply due to the novelty of the therapy and unknowns associated with their behavior in the body.

most desperate situations, patients may see no other options, or may view the years of continuing research as an obstacle to their potential cure. Yet, untested treatments can be dangerous and years of preclinical and clinical research are required to determine which novel stem-cell based therapies are effective and safe. In one example, brain tumors were discovered in a 9-year old boy who travelled to Russia to receive stem cell treatments to his brain; later it was found that the tumors were the result of cells from at least 2 different donors [2]. Even carefully planned and approved studies can go wrong and have unfortu‐ nate results, as in the fatal gene therapy case of Jesse Gelsinger, who received experimen‐

Lau et al reported on the clinics around the world that are exploiting patients' hopes by professing to have effective stem cell therapies for seriously ill patients. These therapies often carry a hefty pricetag. However, they occur in counties which have limited oversight and allow treatment to occur in the absence of credible scientific rationale, transparency, oversight, or

Comprehensive government regulations exist in the US, and several other countries. Below, we describe the U.S. and other government regulations associated with the use of human stem

To protect the public from risks associated with cell therapies and demonstrate the effective‐ ness of treatments, the U.S. FDA and other professional societies such as the ISSCR, and the United States Pharmacopia (USP), have established guidelines for therapies using human cellular and tissue-based products (HCT/Ps). The FDA has statutory authority to prevent the spread of communicable diseases granted under Section 361 of the Public Health Service Act (PHS Act, 42 U.S.C. § 264). HCT/Ps are regulated through a risk-based approach outlined predominantly in 21 C.F.R. Part 1271. Some HCT/Ps are regulated solely under Part 1271 while other HCT/Ps are regulated under both Part 1271 and FDA's Federal Food, Drug, and Cosmetic Act (FDCA, premarket and post- market regulation of medical devices and drugs), & section 351 of the PHS Act for biological products. FDA's regulation focuses on three general areas: 1) limiting the risk of transmission of communicable disease from donors to recipients; 2) establishing manufacturing practices that minimize the risk of contamination; 3) requiring an appropriate demonstration of safety and effectiveness for cells and tissues that present greater

Stem cell therapies show excellent promise for many types of treatments. However, scientific, manufacturing and safety challenges exist. Once the optimal stem cell type is identified for a given treatment (Table 1), there is a requirement to demonstrate the product's safety and efficacy in a clinical setting. Cell therapies must overcome several challenges before they can be considered safe for human use. First, most cell therapies will

**2. Cell Products must follow FDA regulatory guidelines**

tal therapy at University of Pennsylvania[3, 4].

cell and tissues in regenerative medicine.

risks due to their processing or their use [6, 7].

**2.1. FDA's risk-based approach**

patient protections [5].

204 Regenerative Medicine and Tissue Engineering


**Table 1.** Scientific and Manufacturing Challenges in Stem Cell Sourcing *( numbers refer to literature references)* Several stem cell types are studied for their potential use in regenerative medicine, including, but not limited to, embryonic stem cells [20-27], inducible pluripotent stem cells [28-41], bone-marrow stem cells [42-46] and adipose-derived stem cells [47-55]. However, there are challenges with all stem cell types. A major concern with clinical application of iPSCs is their tendency to form tumors and cause cancer. Both ESC and iPSCs form teratoma in vivo, a major obstacle to stem-cell based regenerative medicine by the FDA. Also they are ethically controversial since they require genetic engineering using oncogenes. More recently, proteins have been used to generate piPSCs but the conversion efficiency us quite low. Adult derived BM-MSCs or adipose MSC are limited by their expandability.

In 1993, the US FDA began establishing regulatory and guidance documentation for cell therapies with the issuance of Application of Current Statutory Authority to Human Somatic Cell-therapy and Gene-therapy Products [13] which provided a biologics regulatory frame‐ work for the use of HCT/Ps. Table 2 provides a list of other key regulatory and guidance documents. The tiered risk-based approach means that products which present a lower perceived risk will be less regulated, while products with a larger perceived risk will undergo more extensive controls and examination. Both will require the cell products to be manufac‐ tured following Good Manufacturing Practices (GMP), and Good Tissue Practices (GTP). Additional regulatory requirements will depend on whether the cell product is minimally manipulated or more-than-minimally manipulated.


**Table 2.** Key US FDA Regulatory and Guidance Documents. Over the past 15 years, the FDA has provided several guidance documents for HCT/Ps. A few products such as Genezyme's *Carticel* received approval prior to the issuance of these documents and has been grandfathered in. Many of these guidance documents are issued by CBER, the center within FDA that regulates biological products for human use following applicable federal laws, including the Public Health Service Act and the Federal Food, Drug and Cosmetic Act.

Minimal manipulation is defined by the FDA for cells or nonstructural tissue as processing that does not alter relevant biological characteristics of cells or tissues. HCT/Ps that meet 1271 criteria for regulation solely under section 361 of the PHS Act and the regulations in Part 1271 are called "361 HCT/Ps", and are not subject to any premarket review requirements. The Center for Biologics Evaluation and Research (CBER) has jurisdiction over 361 HCT/Ps.

According to 21 CFR 1271.10, minimal manipulation criteria include:


**a.** is for autologous use;

**1998**

1999

2001

2001

1996

2002

2007

GTP

GCP

**Guidance for Industry: Guidance for human somatic cell therapy and gene**

*Guidance for Industry: Eligibility Determination for Donors of Human Cells, Tissues, and*

*Suitability determination for donors of HCT/Ps; proposed rule*

Current good tissue practice for manufacturers of HCT/Ps;

Human cells, tissues and cellular and tissue-based products (HCT/Ps); establishment registration and listing; final rule

Validation of procedures for processing of human tissues

Public Health Service Act and the Federal Food, Drug and Cosmetic Act.

**1.** The HCT/P is minimally manipulated;

**4.** Either:

inspection and enforcement; proposed rule

206 Regenerative Medicine and Tissue Engineering

intended for transplantation: final guidance

*Good clinical practice, GCP, ICH E6*

*Cellular and Tissue-Based Products*

GMPs GMP 2001

*Guidance for Industry Potency Tests for Cellular and Gene Therapy Products* 2011

Minimal manipulation is defined by the FDA for cells or nonstructural tissue as processing that does not alter relevant biological characteristics of cells or tissues. HCT/Ps that meet 1271 criteria for regulation solely under section 361 of the PHS Act and the regulations in Part 1271 are called "361 HCT/Ps", and are not subject to any premarket review requirements. The Center

**2.** The HCT/P is intended for homologous use only, as reflected by the labeling, advertising,

**3.** The manufacture of the HCT/P does not involve the combination of the cell or tissues with another article, except for water, crystalloids, or a sterilizing, preserving, or storage agent, provided that the addition of water, crystalloids, or the sterilizing, preserving, or storage

**i.** The HCT/P does not have a systemic effect and is not dependent upon the metabolic

**ii.** The HCT/P has a systemic effect or is dependent upon the metabolic activity of living

agent does not raise new clinical safety concerns with respect to the HCT/P; and

for Biologics Evaluation and Research (CBER) has jurisdiction over 361 HCT/Ps.

According to 21 CFR 1271.10, minimal manipulation criteria include:

or other indications of the manufacturer's objective intent;

activity of living cells for its primary function; or

cells for its primary function, and:

**Table 2.** Key US FDA Regulatory and Guidance Documents. Over the past 15 years, the FDA has provided several guidance documents for HCT/Ps. A few products such as Genezyme's *Carticel* received approval prior to the issuance of these documents and has been grandfathered in. Many of these guidance documents are issued by CBER, the center within FDA that regulates biological products for human use following applicable federal laws, including the

**therapy**


For cells, minimal manipulation means processing that does not alter the relevant biological characteristics of cells or tissues. Examples of products regulated as 361 HCT/Ps include bone marrow or blood transplants and organ transplants.

HCT/Ps that do not meet one or more of the four major criteria, are considered more-thanminimally- manipulated HCT/P. FDA has stated that density-gradient separation, cell selection, centrifugation, and cryopreservation constitute minimal manipulation. All processes that manipulate the cell / tissue product such as cell activation, encapsulation, ex vivo expansion, and gene modifications are considered more-than-minimal manipulations. Most advanced cellular therapies meet criteria for the more-than minimally manipulated category [14]. Finally, it is possible to request an informal jurisdictional determination on the level of manipulation from the Tissue Reference Group (TRG), or submit a formal Request for Designation (RFD) from the Office of Combination Products (OCP). Figure 1 is a schematic of regulatory pathway assessment to determine which guidelines apply to a given HCT/Ps product.

#### **2.2. Manufacturing of HCT/Ps requires GTPs**

For HCT/Ps that do not meet the criteria established in Section 1271.10, FDA premarket review is required; this includes obtaining FDA license, approval, or clearance.

All steps in the manufacturing of HCT/Ps will require compliance with Current Good Tissue Practice (cGTPs). cGTPs cover manufacturing facilities and processes. The manufacturing process can be broadly described as 1) procurement of HCT/Ps (donor screening and testing, product recovery), 2) processing of HCT/Ps (tissue or cell recovery /isolation, product han‐ dling, product labeling), 3) storage (e.g. cryopreservation), and 4) distribution. Many of these steps are common to GTPs and GMPs with the goal of safe and effective products via wellcontrolled processes and thorough supporting documentation. Requirements for standard operating procedures (SOPs), labeling controls, and storage requirements also exist.

#### *2.2.1. Procurement*

Therapies with HCT/Ps will require a determination of donor eligibility. For the FDA, donor eligibility is determined based on donor screening and testing for relevant communicable disease agents and diseases, and is required for all donors of cells or tissue used in HCT/Ps, with some exceptions listed in C.F.R. Part 1271.90.

As part of clinical or industry compliance with donor testing requirements, procedures to process, store, label, and package cell products also are needed. Hospitals and companies involved in cell/tissue therapeutics manufacturing must establish quality programs which consist of a comprehensive system for manufacturing and tracking HCT/Ps. The quality program must follow CGTP requirements, and be designed to prevent, detect, and correct deficiencies that may lead to circumstances that increase the risk of introduction, transmission, or spread of communicable diseases.[6, 7]

#### *2.2.2. Processing*

The implementation of a Quality Assurance (QA) program includes principles of good manufacturing practice (GMP) and a quality control (QC) system. A QC system is required to ensure safety and efficacy of cell applications. GMP regulations apply to all phases of cell/ tissue collection, processing and expansion, and storage. GMP quality practices are required for HCT/Ps to be used for clinical procedures and INDs. A compliant quality program for record and process control is a critical part of a QC system.

A compliant material control program is essential for FDA licensure. During review of new license applications, clinics and companies are asked to provide detailed descriptions of the manufacturing process and documentation of source country for all materials of animal origin. Additionally, for FDA-regulated products intended for administration to humans, companies must minimize any chance that BSE could be introduced into products during the manufac‐ turing process and ensure that all materials are used as intended in the processing and are contamination free. Subsequently, a program for control of materials used in the process is necessary to meet FDA compliance and product safety.

#### *2.2.3. Storage*

If the HCT/P product involves cryopreservation, then compliance requires that the process includes an understanding of the shelf-life and how the freezing & storage process affects the HCT/Ps to complete the quality testing program. Banked cells should be stored under conditions shown to be suitable for long-term stability. Cell/tissue stability under the freezing and storage conditions should be validated using cell recovery or viability data. It is expected that establishment of a stability program for a banking process will lead to the development of quality products over a long term storage period and provide confidence that they will be effective in clinical applications.

#### *2.2.4. Distribution testing*

For the lot release of patient's cells/tissues for clinical use, standards for in-process and final product quality must be established. Specifically for FDA licensure, companies must submit their facility controls, process controls, and product standards designed with scientific principles to ensure the safety and effectiveness of all HCT/Ps products. This again is based on SOPs and controls for adherence to the cGTP, Current Good Manufacturing Practice (cGMP) and 21 CFR 1271 requirements. Product lot release specifications ensure that all products are produced in a safe and consistent manner and should be effective in clinical applications. In order to meet HCT/Ps regulations, product lot release specification should include testing for cell phenotype to confirm purity, potency, and identity.

The application for licensure requires that companies demonstrate that the HCT/P product standards and procedures are based on good science, and thorough and extensive data. A comprehensive product characterization program is needed to understand the products and how they may be clinically beneficial. During the application process, the FDA may request that the hospital or company applicant expand on a concept or further explain the rationale/ approach or provide additional data. FDA premarket review and licensing is considered a lengthy and arduous process, however new products applicants may benefit by the recent approvals of several cell-based products (Table 3).

program must follow CGTP requirements, and be designed to prevent, detect, and correct deficiencies that may lead to circumstances that increase the risk of introduction, transmission,

The implementation of a Quality Assurance (QA) program includes principles of good manufacturing practice (GMP) and a quality control (QC) system. A QC system is required to ensure safety and efficacy of cell applications. GMP regulations apply to all phases of cell/ tissue collection, processing and expansion, and storage. GMP quality practices are required for HCT/Ps to be used for clinical procedures and INDs. A compliant quality program for

A compliant material control program is essential for FDA licensure. During review of new license applications, clinics and companies are asked to provide detailed descriptions of the manufacturing process and documentation of source country for all materials of animal origin. Additionally, for FDA-regulated products intended for administration to humans, companies must minimize any chance that BSE could be introduced into products during the manufac‐ turing process and ensure that all materials are used as intended in the processing and are contamination free. Subsequently, a program for control of materials used in the process is

If the HCT/P product involves cryopreservation, then compliance requires that the process includes an understanding of the shelf-life and how the freezing & storage process affects the HCT/Ps to complete the quality testing program. Banked cells should be stored under conditions shown to be suitable for long-term stability. Cell/tissue stability under the freezing and storage conditions should be validated using cell recovery or viability data. It is expected that establishment of a stability program for a banking process will lead to the development of quality products over a long term storage period and provide confidence that they will be

For the lot release of patient's cells/tissues for clinical use, standards for in-process and final product quality must be established. Specifically for FDA licensure, companies must submit their facility controls, process controls, and product standards designed with scientific principles to ensure the safety and effectiveness of all HCT/Ps products. This again is based on SOPs and controls for adherence to the cGTP, Current Good Manufacturing Practice (cGMP) and 21 CFR 1271 requirements. Product lot release specifications ensure that all products are produced in a safe and consistent manner and should be effective in clinical applications. In order to meet HCT/Ps regulations, product lot release specification should include testing for

or spread of communicable diseases.[6, 7]

208 Regenerative Medicine and Tissue Engineering

record and process control is a critical part of a QC system.

necessary to meet FDA compliance and product safety.

cell phenotype to confirm purity, potency, and identity.

*2.2.2. Processing*

*2.2.3. Storage*

effective in clinical applications.

*2.2.4. Distribution testing*


**Table 3.** Approved Cell Therapy Products by the U.S. FDA and non-3rd World Countries. Several cell products have received US approval[99] and are in current use for a number of patients. Most US approved products are for autologous use, only Apilgrafs foreskin cells are used allogeneically. Osiris recently received conditional approval for allogeneic use of mesenchymal stem cells in pediatric graft-vs-host disease.
